E.I.DU  PONT  DE  NEMOURS  POWDER  COMPANY, 

WILMINGTON,  DELAWARE,  U.S.A. 
ESTABLISHED      I8OE . 


BLASTING  MACHINES 

ELECTRIC  FUZES  ELECTRIC  SQUIBS 

LEADING  WIRE      CONNECTING  WIRE 

GALVANOMETERS       LEADING  WIRE  REELS 

THAWING  KETTLES     RHEOSTATS 

SAFETY  FUSE      BLASTING  CAPS 

BLASTING  MATS      CAP  CRIMPERS 

TAMPING  BAGS 


E.I.DUPONTDENEMOUR5  POWDER  COMPANY! 

WILMINGTON ,  DELAWAREU5.A. 


Copyright,  1911 

E.  I.  du  Pont  de  Nemours  Powder  Co. 
Wilmington,  Del. 


PRESS    OF 

DANDO    COMPANY 

PHILADELPHIA 


Foreword 

LTHOUGH  the  explosive  itself  very 
naturally  demands  first  consideration 
when  blasting  is  to  be  done,  the  fact 
must  not  be  overlooked  that  it  cannot 
be  properly  exploded  without  certain 
materials  and  appliances  especially 
designed  for  the  purpose,  and  which  are 
commonly  known  as  "  Blasting  Supplies."  In  addition  to 
those  articles  necessary  to  develop  the  energy  of  a  charge 
of  explosives,  there  are  other  devices  which,  although 
they  may  not  be  absolutely  requisite,  contribute  to  safety, 
certainty  and  economy  in  the  use  of  explosives,  and  these 
are  also  included  in  the  category  of  Blasting  Supplies. 

The  importance  of  keeping  Blasting  Supplies  up  to 
the  highest  standard  in  every  respect  cannot  be  over- 
estimated, for  the  very  best  grade  costs  but  a  trifle  in 
comparison  with  the  charge  of  explosives  with  which 
they  are  used.  It  is  poor  economy  to  attempt  to  deto- 
nate explosives  with  an  inferior  article,  for  this  always 
results  in  a  considerable  waste  of  the  value  of  the  explos- 
ives. More  than  a  hundred  years'  experience  in  the 
manufacture,  sale  and  use  of  all  kinds  of  explosives  has 
taught  us  that  the  popularity  of  our  products  depends 
entirely  on  the  results  which  consumers  have  with  them. 
With  this  in  view,  we  must,  from  a  standpoint  of 
"  good  business,"  if  from  no  other,  recommend  only  a 
high  quality  of  Blasting  Supplies. 


251752 


INDEX 


ADVANTAGES  OF  STRONG  DETONATORS  -        85 

BLASTING  BY  ELECTRICITY          -           -           -         •'.'          .  5 

BLASTING  CAPS              -            -         \    .        -            .            -  -        63 

BLASTING  MACHINES         -           .                       - "                     .  29 

BLASTING  MATS            -           ...           -           -  82 

BLASTING  SUPPLIES  AND  THEIR  USE  -           ...  1 

CAP  CRIMPERS    -           .           .           .           -           .           .  -77 

CONNECTING  WIRE             ...           .           .           .  39 

DELAY  ELECTRIC  FUZES          -                       -           -           -  -17 

ELECTRIC  FUZES      -                       „           .           .           .  11 

ELECTRIC  SQUIBS           -           -                       -           -           -  -23 

ELEMENTARY  PRINCIPLES  OF  ELECTRICITY   -           -           -  91 
GALVANOMETERS          -.-....        43 

INTRODUCTION          ...,„....  ] 

LEADING  WIRE  ...  ....        39 

LEADING  WIRE  REEL                                 -                                   -  40 

PRECAUTIONS  TO  BE  OBSERVED  WITH  EXPLOSIVES    -  -114 

RHEOSTATS    -                        55 

SAFETY  FUSE      -  .  -  .  ....        67 

TAMPING  BAGS        -           -           .                       -           -          \  81 

THAWING  KETTLES  78 


INTRODUCTION 


Blasting  Supplies  and  Their  Use 

LECTRIC  Fuzes  are  the  detonators  used  when  a 
high  explosive,  such  as  dynamite,  is  fired  electric- 
ally.    They  consist  of  a  copper  capsule,  or  shell, 
containing  a  detonating  charge  surrounding  a  fine 
platinum  "bridge,'*  which  joins  the  tips  of  two 
insulated  copper  wires  of  various  lengths.     The 
ends  of   the    copper  wires  are    secured   in    the 
copper  shell  by  a  composition  plug,  which  also 
serves  to  keep  moisture  and  water  away  from  the  charge.     The 
electric  fuze  is  detonated  when  sufficient  current  is 

Electric  passed  through  the  copper  wires,  and  across  the 

Fuzes  .  5  ill 

platinum  bridge,  to  heat  the  latter  to  a  temperature 

high  enough  to  ignite  the  charge  surrounding  it. 

Delay  Electric  Fuzes  can  be  used  to  advantage  in 
Delay         certain  classes  of  tunnel  or  shaft  excavating.    These 

Electric  Fuzes  . 

are  made  so  that  a  very  short  space  of  time 
intervenes  between  their  ignition  by  the  electric  current  and 
their  detonation.  By  their  use,  it  is  possible,  with  but  one  opera- 
tion of  the  blasting  machine,  to  fire  one  section  of  a  blast, 
sufficiently  ahead  of  the  following  section,  for  the  material  in 
the  first  to  be  out  of  the  way  when  the  next  is  blasted. 

When  several  charges  of  explosives  are  to  be 
detonated  at  one  time  with  electric  fuzes,  it  is  neces- 
sary (unless  the  electric  fuze  wires  are  long  enough 
to  reach  between  the  bore  holes)  to  join  them  with  Connecting 
Wire.  Insulated  copper  wire  is  used  for  this  purpose. 


Leading  Wire,    which   is    also   insulated   and   in 
order  to  reduce  resistance  is  of  a  larger  size  than 
connecting  wire,  connects  the  electric  fuzes  in  the  first 
and  in  the  last  bore  hole  with  the  source  of  the  electric  current. 

The  current  for  electric  blasting  is  sometimes  taken 
Machines  ^rom  a  Power  or  luting  system,  but  the  source  of 

current  commonly  used  is  known  as  a  Blasting 
Machine.  Although  manufactured  in  several  sizes  and  styles, 
they  are  usually  designed  on  the  same  general  principle. 

Owing  to  the  many  difficulties  generally  attending 

Galvanom-      yastmg    ^h   as  wet   or   co\£  weather,  water  in 
eters 

bore  holes,  necessity  for  hurry,  and  so  on,  it  not 

infrequently  happens  that  electric  fuze  wires  are  stripped  or 
broken  in  tamping,  connections  are  improperly  made,  poorly 
insulated  and  leaky;  or  the  circuit  is  broken  or  interrupted  in 
some  other  way,  which  results  in  the  misfire  of  the  explosives  in 
some  or  all  of  the  bore  holes,  causing  serious  loss  and  delay.  In 
order  to  eliminate  this  trouble  as  far  as  possible,  a  Galvanometer 
has  been  designed,  for  testing  out  the  blasting  circuit  before 
firing.  It  is  possible  with  this  instrument  to  detect  a  break  or 
any  considerable  leaks  in  the  blasting  circuit.  It  will  also  detect 
extensive  leaks  or  serious  defects  in  the  electric  fuzes  and  locate 
the  points  at  which  the  trouble  exists. 

The  kind  of  work  on  which  blasting  machines  are 
used  is  largely  responsible  for  rough  and  careless 
handling,  which  often  wears  them  out  rapidly.  The  Rheostat  is 
a  simple  but  effective  instrument,  which  should  be  used  from  time 
to  time  to  test  the  capacity  of  blasting  machines,  so  that  there 
will  be  no  danger  of  overloading  them. 

If  the  leading  wire  is  to  be  kept  in  good  condition, 
an(^  Dandled  easily  an(l  quickly,  a  Leading  Wire 
Reel  is  necessary. 


When  blasting  powder  is  the  explosive  used,  Electric 

Electric  Squibs  may  take  the  place  of  electric  fuzes.    They 

Squibs  '  .  i         •      r 

are  made  on  the  same  principle  as  electric  tuzes, 
but  cost  less,  as  a  heavy  paper  shell  replaces  the  copper  cap  of 
the  electric  fuze.  As  the  charge  in  Electric  Squibs  does  not 
detonate,  but  burns  or  flashes,  they  will  not  detonate  dynamite  or 
other  high  explosives,  and  can  be  used  only  with  blasting  powder 
or  similar  low  explosives. 

Blasting    Caps  are  used  to   detonate   high  explos- 

Blastmg  •         when  it  is  not  necessary   to   fire   more   than 

Caps  '  .  J 

one  charge  at  a  time,  or  when  tor  some  other  reason 

electric  firing  is  not  feasible.  They  consist  of  a  copper  shell 
similar  to  that  of  the  electric  fuze,  and  which  contains  the  same 
kind  of  a  charge.  The  charge  in  the  blasting  cap,  however,  is 
not  ignited  electrically,  but  by  a  section  of  safety  fuse  on  the  end 
of  which  the  blasting  cap  must  be  crimped. 

Safety  Fuse  consists  of  a  small  train  of  fine  grain 
p  e1  fuse  powder  which  forms  the  core  of  a  rope  of 

hemp,  cotton  or  tape,  generally  covered  with  water 
proofing  mixture.  It  is  used  for  detonating  blasting  caps  as 
described  above,  or  for  igniting  directly  charges  of  blasting 
powder  into  which  it  carries  a  spark. 

The  Cap  Crimper  is  a  very  convenient  and  service- 
able little  tool,  which  is  used  to  attach  the  blasting 

Crimpers 

cap  securely  to  the  sarety  ruse,     oome  styles  are 

equipped  with  a  fuse  cutter. 

Many    high    explosives    containing    nitroglycerin 
awing         freeze  very  easily,  and  become  insensitive  at  tem- 
peratures from  45°  F.  to  50°  F.    These  explosives 
cannot   be   used   effectively   in    cold  weather,    unless    they    are 
thoroughly  thawed  and  kept  warm  until  they  are  loaded  in  the 
bore  hole.     Thawing  Kettles  are  used  for  this  purpose.     There 
are    several    different    designs,    but    all    are    constructed   with 
a  warm  water  jacket  surrounding  the  explosives  compartment 


Tamping  Bags  are  paper  containers  for  sand,  clay 
or  other  material  with  which  horizontal  or  pitching 
bore  holes,  or  "  uppers/*  are  to  be  tamped.  They 

are  also  used  when  making  blasting  powder  into  cartridges  for 

use  in  similar  bore  holes. 

Blasting  Mats  are  woven  mats  of  rope,  which  are 
astmg  spread  on  the  ground  above  the  bore  holes,  when 

blasting  is  done  where  flying  pieces  of  rock  will  be 
dangerous.  If  heavy  charges  of  explosives  are  used,  it  is  the 
custom  to  place  logs  or  railroad  ties  directly  over  the  bore  holes, 
and  the  blasting  mats  on  top  of  these. 


Blasting  by  Electricity 


[LASTING  by  electricity  is  generally  conceded  to 
be  the  most  effective  and  economical  system,  and 
to  surpass  any  other  in  safety,  expedition  and 
certainty.  In  work  where  it  is  possible  to  blast 
more  than  one  charge  at  a  time,  it  will  nearly 
always  be  found  advantageous  to  do  so.  This 
can  only  be  accomplished  by  electric  firing.  When 
several  charges  are  fired  simultaneously  each  tends 
to  help  the  other,  both  in  turning  out  and  in  breaking  up  the 
material  blasted,  with  the  result  that  a  greater  amount  of  work 
is  done  by  a  given  quantity  of  explosives  than  if  the  several 
charges  were  fired  successively.  It  is  possible  also  to  better  pro- 
tect against  water  and  other  causes  of  misfire  the  appliances  used 
in  electric  blasting,  thus  insuring  greater  certainty.  As  delayed 
explosions,  or  "hang  fires,"  are  hardly  possible,  and  as  the  blaster 
can  always  be  a  considerable  distance  away  from  the  explosive 
when  it  detonates,  this  system  reduces  the  possibility  of  accident 
to  a  minimum. 

rNo  method  of  blasting  in  gaseous  or  dusty  coal  mines,  other 
than  the  electrical  one,  deserves  consideration  because  in  all  others 
the  ignition  in  the  open  of  some  burning  substance  is  necessary, 
even  though  a  device  be  used,  whereby  the  safety  fuse  or  squib 
can  be  ignited  without  exposing  an  open  light  or  flame  in  a 
gaseous  place. 

It  is  believed  by  many  authorities  that  disastrous  explosions 
in  coal  mines  have  been  caused  by  a  blown-out  shot  occurring 
shortly  after  a  number  of  other  blasts  have  been  fired.  This 
cannot  happen  if  the  firing  is  done  by  electricity,  when  as  many 
shots  as  desired  are  fired  simultaneously.  In  submarine  or  other 
very  wet  work,  no  other  system  is  feasible.  In  underground 
work,  where  ventilation  is  not  good,  burning  safety  fuse  increases 


Blasting  Circuit  Connected  in  Series 


the  smoke  and  fumes  very  materially.  It  is  not  uncommon  for 
the  fire  to  break  through  the  side  of  the  fuse,  and  ignite  the 
charge  of  explosives  before  detonating  the  blasting  cap,  resulting 
in  poor  execution  and  increase  in  fumes.  This  cannot  occur 
when  the  blasting  is  done  by  electricity. 

The  equipment  necessary  for  electric  blasting  is  as  follows: 

Electric  Fuzes  Connecting  Wire 

Leading  Wire  Blasting  Machine 

The  following  will  also  prove  of  much  assistance  and  very 
often  effect  a  saving  of  both  time  and  money: 

Leading  Wire  Reel  Galvanometer 

Rheostat 

If  the  explosive  used  is  blasting  powder,  and  not  a  high 
explosive,  Electric  Squibs,  which  are  less  expensive,  should  re- 
place Electric  Fuzes  in  the  above  list. 

When  the  source  of  the  electric  current  is  a  blasting  machine, 
or  "battery,"  of  the  usual  type,  the  bore  holes  are  connected  in 
series;  that  is,  one  wire  of  the  electric  fuze  in  the  first  bore  hole 
is  joined  (using  connecting  wire  if  necessary)  to  one  wire  of  the 
electric  fuze  in  the  second  bore  hole,  and  the  other  wire  of  this 
electric  fuze  to  one  wire  of  the  electric  fuze  in  the  third  bore 
hole,  and  so  on,  until  all  of  the  bore  holes  are  connected  together 
with  a  free  electric  fuze  wire  in  the  first  and  the  last  bore  holes; 
these  free  wires  are  to  be  connected  to  the  leading  wires  and 
the  leading  wires  to  the  blasting  machine. 

The  Blasting  Machines,  described  in  this  catalogue,  are 
made  for  series  connecting  only  and  connections  should  not  be 
made  in  "parallel,"  or  any  modification  thereof.  (See  illustration, 
page  6). 

When  making  connections,  care  must  be  taken  to  see  that 
all  metal  parts  joining  each  other  are  scraped  bright  and  clean. 
Another  point  of  particular  importance  is  that  no  part  of  the  cir- 
cuit which  is  not  thoroughly  insulated  should  come  in  contact 
with  any  other  uninsulated  part  of  the  circuit,  or  with  water,  or 


with  wet  or  damp  ground.      In  order   to  accomplish  this,   all 
bare  joints  should  be  covered  with  insulating  tape. 

When  making  connections,  do  not  loop  the  wires,  but  twist 
them  tightly  together. 

Looped  Wires— The  WRONG  Way 


Twisted  Wires -The  RIGHT  Way 


The  attempt  to  use  old  and  damaged  leading  wire  or 
connecting  wire,  is  a  great  mistake  and  is  often  the  cause  of  mis- 
fires. One  of  the  principal  objections  to  their  use  is  that  the 
wire  itself  frequently  breaks  inside  the  insulation,  which  will 
remain  intact.  When  this  occurs,  the  ends  of  the  wire  may 
touch  and  the  circuit  seem  all  right  when  tested,  but  a  very  slight 
movement  of  the  wires  afterwards  may  pull  these  ends  apart, 
breaking  the  circuit  and  causing  a  misfire.  A  break  of  this  kind 
is  not  easily  located,  and  sometimes  is  responsible  for  the  loss  of 
the  time  of  many  workmen  waiting  for  the  shot  to  be  fired. 


Victor  Electric  Fuzes 
Delay  Electric  Fuzes 


Victor  Electric  Fuzes 

ICTOR  Electric  Fuzes  are  made  in  three  different 
strengths — No.  6,  No.  7  and  No.  8,  each  of 
which  is  put  up  with  insulated  copper  wires  of 
the  following  lengths: 


4'  10' 

6'  12' 

8'  14' 


16' 

18' 
20' 


22' 
24' 
26' 


28' 
30' 


Special  lengths  not  shown  above  will  be  manufactured  on 


order. 


No.  6  No.  7  No.  8 

Victor  Electric  Fuzes  (actual  size) 


11 


The  following  table  describes  fully  Victor  Electric  Fuzes  of 
different  strengths: 

Grade.    ......: No.  6  No.  7  No.  8 

Color  of  Label Red  Brown  Green 

Length  of  Shell 1TV  W"  \ 

Caliber  of  Shell 273"  .273"  .273" 

.....       (r.          (Grains   ....     15.43  23.15  30.86 
Weight  of  Charge  lGrams                        ,  QQ                          K50  2.00 

Nothing  weaker  than  Victor  No.  6  electric  fuzes  can  be 
relied  on  to  develop  the  full  force  of  any  high  explosives  that 
are  not  too  sensitive  to  handle  or  use  with  any  degree  of  safety. 

Victor  Electric  Fuzes  are  furnished  for  submarine  work,  with 
a  special  gutta  percha  covering,  which  is  highly  water  resisting. 

Victor  Water  Proof  Electric  Fuzes,  having  a  special  insula- 
tion, are  also  furnished  for  submarine  and  other  very  wet  work. 


GUTTAPERCHA        COVERED 
(FOR   SUBMARINE    WORK) 


SECTION     OF    GUTTAPERCHA     COVERED 
(FOR   SUBMARINE     WORK) 

The  illustration  below  shows,  in  section,  an  Electric  Fuze. 
"A"  is  the  shell  of  copper,  having  a  corrugation  thrown  out 
from  the  inside,  which  holds  the  composition  plug  more  firmly  in 
place ;  "  B "  is  the  chamber  containing  the  explosive  charge ; 
"C,"  the  insulated  copper  wires  entering  the  cap;  "D,"  the 

D, 


E     D 


bare  ends  of  the  copper  wires,  projecting  through  the  plug 
into  the  charge ;  "  E,"  the  small  platinum  wire  or  "  bridge  "  soldered 
to  and  connecting  the  two  ends  of  the  copper  wires,  which  is  heated 
by  the  electric  current;  "  F,"  the  composition  plug  holding  the  fuze 
wires  firmly  in  place ;  "  G,"  the  filling  material. 

Electric  Fuzes  are  packed  in  pasteboard  cartons,  which  are 
enclosed  in  heavy  wooden  cases.     The  cartons  contain  either 

12 


25  or  50,  depending  on  the  length  of  the  wires.  Electric  fuzes 
with  wires  from  4  feet  to  1 6  feet  long  are  packed  for  domestic 
trade  500  to  the  case,  while  those  with  longer  wires  are  packed 
250  to  the  case.  The  number  of  electric  fuzes,  with  wires  of 
different  lengths,  to  the  case,  the  dimensions,  and  the  gross  and 
net  weight  of  case  for  domestic  shipment  are  given  in  the  table 
on  page  1  4. 

The  storage  of  electric  fuzes  should  always  be  given  care- 
ful attention  by  the  consumer.  If  they  are  permitted  to  remain 
for  a  considerable  period  of  time  in  a  very  warm  place,  the  water 
proofing  material  in  the  insulation  dries  out  to  such  an  extent 
that  the  insulation  may  break  when  the  wires  are  bent,  and  mis- 
fires result  if  an  attempt  is  made  to  use  them  in  wet  work. 

The  explosive  charge  in  the  electric  fuzes  is  very  easily 
affected  by  moisture,  and  if  they  are  stored  in  a  damp  or  wet 
place  they  may  deteriorate.  This  charge  is  also  very  sensitive, 
and  may  be  exploded  by  a  moderately  hard  knock  or  jar. 
Electric  fuzes  should  therefore  be  handled  carefully.  Careful 
handling  is  also  necessary  on  account  of  the  delicate  bridge  wire 
(see  illustration,  page  1 2),  which  may  be  broken,  and  which 
when  broken  renders  the  electric  fuze  absolutely  useless.  The 
wires  must  not  be  bent  sharply  or  forcibly  separated  at  the  point 
where  they  enter  the  copper  cap,  as  this  may  break  or  loosen 
the  filling  material  and  permit  water  to  enter  and  damage  the 
charge  in  the  electric  fuze. 

The  correct  way  to  prime  a  high  explosive  cartridge  with 
an  electric  fuze  is  to  unfold  the  paper  on  one  end  of  the  cartridge 
and  insert  the  fuze  cap  in  the  center,  pointing  it  directly  toward 
the  opposite  end;  then  fold  the  paper  about  the  two  wires  and 
tie  it  firmly  with  strong  twine.  The  primer  may  also  be  made 
by  inserting  the  fuze  cap  in  the  side  of  the  cartridge,  near  the 
end,  and  pointing  it  downward  toward  the  opposite  end,  the 
wires  to  be  tied  to  the  side  of  the  cartridge.  The  electric 
fuze  should  always  be  placed  so  that  the  loaded  end  will  point 
toward  the  main  portion  of  the  charge  of  explosives  it  is  to 
detonate.  The  hole  for  the  fuze  cap  should  be  made  in  the 
cartridge  with  a  pointed  stick  about  the  size  of  a  lead  pencil. 
The  common  custom  of  taking  one  or  more  loops,  or  half  hitches, 
around  the  cartridge  with  the  wires  themselves,  after  inserting 

13 


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14 


the  fuze  cap  in  a  hole  made  diagonally  in  the  side  of  the 
cartridge  near  one  end,  is  always  to  be  condemned.  The  prin- 
cipal objection  is  that  the  looping  of  the  wires  may  break  the 
insulation  causing  short  circuits  or  leakage  of  current  in  wet 
work,  or  may  even  break  the  wires  themselves.  Also,  when  a 
fuze  cap  from  1  T9-g  inches  to  2  inches  long  is  pushed  into  the  side 
of  a  cartridge  1  inch,  1  /^  inches,  or  even  1  Y*  inches  in  diameter, 
it  very  often  happens  that  the  point,  where  the  principal  part 
of  the  detonating  charge  is  located,  goes  entirely  through  the 
explosive  itself,  even  though  it  may  not  break  through  the  paper. 
As  it  is  often  the  custom,  when  priming  in  this  way,  to  point 
the  fuze  cap  diagonally  toward  the  end  of  the  cartridge,  which 
will  be  nearest  the  outside  or  top  of  the  charge,  it  can  readily  be 
seen  that  any  pull  on  the 
wires,  hard  enough  to 
affect  the  position  of  the 
cap,  will  tend  to  bring  it 
more  to  a  right  angle 
with  the  long  axis  of  the 
cartridge,  and  thus  force 
the  point  still  farther  out 
of  the  opposite  side.  (See 
accompanying  illustra- 
tions.) While  this  does  not  always  cause  a  failure,  it  is  quite 
possible  that  lost  shots  may  be  attributed  to  it,  especially  when 

cartridges  of  small 
diameters  are  used. 
The  series  of  illustra- 
tions on  page  66  show 
very  clearly  the  proper 
method  of  making  a 
primer  with  blasting 
cap  and  fuse.  The 
same  method  should 
be  followed  when  an 
Electric  Fuze  is  used.  Although  it  may  take  a  little  longer  to 


1st  Position 


2d  Position 
( T>ue  to  hard  pull  on  the  wires) 


15 


make  a  primer  in  this  way,  it  is  probable  that  the  reduction  in  the 
number  of  misfires  will  much  more  than  repay  for  the  trouble 
taken. 

Care  must  be  taken  when  tamping  the  bore  hole  not  to 
break  either  the  electric  fuze  wires  or  the  insulation  on  them,  or 
to  pull  the  electric  fuze  cap  out  of  the  primer.  Many  misfires 
are  probably  due  to  carelessness  in  loading  and  tamping  bore  holes. 

Although  electric  fuze  wires  are  well  insulated,  they  are  not 
intended  for  extreme  conditions,  and  if  used  in  water,  particularly 
underpressure,  they  may  "leak";  that  is,  the  electric  current, 
or  a  part  of  it,  may  "short  circuit"  instead  of  passing  through  the 
bridge  wire,  which  is  of  high  resistance.  Therefore,  more  current 
is  necessary  to  insure  good  results  in  wet  work  than  in  dry  work, 
unless  electric  fuzes  with  special  insulation  for  wet  work  are 
used.  These  specially  insulated  electric  fuzes  are  called  Victor 
Water  Proof  Electric  Fuzes. 

In  order  to  reduce  as  much  as  possible  the  expense  of  elec- 
tric firing  in  gaseous  or  dusty  coal  mines,  we  manufacture  Victor 
No.  6  Electric  Fuzes  with  Iron  Wires  for  this  purpose  or  for 
other  work  where  Electric  Fuzes  with  wires  longer  than  8 
feet  are  not  required.  We  recommend  nothing  weaker  than 
Victor  No.  6  Electric  Fuzes  to  detonate  "Permissible  Explosives." 
Electric  fuzes  with  iron  wires  cost  less  than  do  those  with  copper 
wires,  but  will  not  prove  satisfactory  under  all  conditions  of  elec- 
tric blasting.  The  principal  reason  for  this  is  that  iron  wire,  even 
when  in  good  condition,  is  much  inferior  to  copper  wire  as  an 
electric  conductor.  Practically  six  times  as  strong  a  current  is 
required  to  fire  an  Electric  Fuze  with  iron  wires  as  will  fire  one 
with  the  same  length  of  copper  wires.  Iron  wire  also  corrodes  much 
more  readily  than  copper  wire.  Victor  No.  6  Electric  Fuzes 
are  made  with  iron  wires  4  feet,  5  feet,  6  feet  and  8  feet  long. 
They  will  be  furnished  with  longer  wires  if  desired,  but  we  do 
not  recommend  them,  because  of  the  poor  conductivity  of  iron 
wire  referred  to  above.  They  are  packed  in  the  same  way  as 
Electric  Fuzes  with  copper  wires,  and  require  the  same  careful 
storage  and  handling. 

16 


Method  of  Connecting  No  Delay,  First  Delay  and  Second  Delay  Electric  Fuzes 


Du  Pont  Delay  Electric  Fuzes 

N  some  kinds  of  blasting,  particularly  in  tunnel 
work,  it  is  necessary  to  blast  each  round  of  bore 
holes  in  sections,  and  it  is  generally  of  consider- 
able advantage  in  saving  time  if  this  can  be 
arranged  so  that  it  will  not  be  necessary  to  return 
to  the  working  face  after  the  first  section  has 
been  blasted.  When  fuse  and  blasting  caps 
are  used  to  detonate  the  explosive,  the  sections  of 
fuse  for  the  different  bore  holes  are  cut  in  different  lengths  so 
that  the  charges  will  explode  in  the  proper  sequence  if  the  fuses 
are  lighted  at  about  the  same  time.  There  is  practically  no  limit 
to  the  number  of  charges  which  can  be  exploded  in  sequence 
with  fuse  and  blasting  caps  in  this  way,  but  under  most  conditions 
there  is  nothing  to  be  gained  by  dividing  the  round  of  holes  into 
more  than  three  sections.  ,  When  the  electric  system  of  blasting 
is  in  effect,  this  can  be  accomplished  on  a  single  application  of  the 
electric  current  by  using  "No  Delay,"  "First  Delay"  and 
"  Second  Delay "  Electric  Fuzes  in  the  same  blasting  circuit. 
The  "  No  Delay "  is  a  special  instantaneous  electric  fuze,  manu- 
factured for  use  with  the  "First  Delay"  and  "Second  Delay," 
and  will  not  give  satisfactory  results  if  used  in  the  same  blasting 
circuit  with  Victor  or  any  other  instantaneous  electric  fuzes,  nor 
can  any  instantaneous  fuze  other  than  the  "No  Delay "  be  used 
satisfactorily  with  "  First  Delay  "  and  "  Second  Delay  "  Electric 
Fuzes.  As  signified  by  their  name,  "  No  Delay  "  Electric  Fuzes 
detonate  at  the  instant  the  electric  current  passes  through  them. 
"  First  Delay  "  and  "  Second  Delay  "  Electric  Fuzes  contain  a 
slow  burning  substance  which  is  ignited  by  the  electric  spark  and 
which,  after  burning  a  short  period  of  time,  ignites  the  detonating 
composition  below  it.  The  burning  speed  of  this  slow  burning 

2  17 


No  Delay  Electric  Fuze 
(Actual  Size) 


First  and  Second  Delay  Electric 
Fuzes  (Actual  Size) 


18 


substance  cannot  be  made  absolutely  uniform  under  all  condi- 
tions, and  consequently  Delay  Electric  Fuzes  of  the  same  period 
in  a  blasting  circuit  may  not  all  explode  simultaneously.  There 
is,  however,  always  a  distinct  period  of  time  between  the  explosion 
of  the  "  No  Delays  "  and  of  the  quickest  of  the  "  First  Delays  " 
and  between  the  slowest  of  the  "  First  Delays  "  and  the  quickest 
of  the  "  Second  Delays."  This  insures  that  section  of  the  round 
which  is  primed  with  the  "  No  Delays  "  being  blasted  out  before 
the  "First  Delays"  explode  and  the  section  primed  with  the  "  First 
Delays  "  being  blasted  out  before  the  "  Second  Delays"  explode. 

These  electric  fuzes  are  easily  distinguished  from  each  other 
and  from  Victor  electric  fuzes  by  the  color  of  the  wires,  the 
"  No  Delay "  wires  being  red,  "  First  Delay "  white  and 
"Second  Delay"  blue. 

These  electric  fuzes  require  the  same  careful  handling  and 
storing  as  do  Victor  electric  fuzes.  They  are  made  in  the  No. 
6  (red  label)  grade  only  and  with  wires  of  the  same  length  as 
those  of  Victor  electric  fuzes. 


19 


Electric  Squibs 


Electric  Squibs 

VER  since  blasting  powder  first  came  into  use, 
the  advantage  of  igniting  the  charge  in  the  center 
has  been  evident  to  all,  particularly  when  this 
charge  is  distributed  for  a  foot  or  more  along  a 
bore  hole  of  comparatively  small  diameter. 

When  a  charge  of  blasting  powder  in  a  bore 
hole  is  ignited  at  one  end,  it  is  always  possible 
for  some  of  the  coal  or  rock  to  fall  before  the 
entire  charge  is  exploded,  and  thus  cut  off  for  an  instant  the 
remainder  of  the  charge.  This  is  most  likely  to  happen  when 
large  charges  are  ignited  at  the  end  nearest  the  mouth  of  the 
bore  hole.  Then  more  or  less  of  the  powder  at  the  back  of 
the  bore  hole,  where  the  burden  is  usually  the  heaviest,  does 
very  little  execution,  and  a  large  flame  and  a  great  volume  of 
smoke  are  projected  into  the  working  place. 

Attempts  to  ignite  the  charge  at  the  center  are  sometimes 
made  by  extending  the  fuse  to  that  point;  but  this  is  seldom 
successful,  owing  to  the  fact  that  most  fuse  will  spit  fire  from  the 
sides  and  ignite  the  charge  where  the  fuse  enters  it.  Even  the 
very  best  triple  tape  and  gutta  percha  fuse  will  do  this  occasion- 
ally. The  expense  attached  to  the  use  of  the  highest  quality  of 
fuse  has  caused  this  method  of  igniting  charges  of  blasting  pow- 
der in  bore  holes  to  be  practically  abandoned. 

"  Miner's  squibs,"  often  used  for  igniting  blasting  powder 
charges  in  bore  holes,  are  sometimes  uncertain  in  their  rate  of 
burning,  and  may  give  but  little  time  for  the  blaster  to  reach  a 
place  of  safety  after  lighting  them.  This  makes  it  necessary, 
when  a  number  of  shots  are  ready  to  be  fired,  for  the  blaster  to 
return  to  the  face  several  times,  causing  the  loss  of  valuable  time. 

23 


All  of  these  disadvantages  are  overcome  by  the  use  of  the 
Du  Pont  Electric  Squib.  These  Electric  Squibs  are  similar  in 
general  appearance  to  Victor  Electric  Fuzes,  but  have  a  heavy 
paper  cap  instead  of  a  copper  one.  The  charge  in  this  cap  does 
not  detonate  like  that  in  electric  fuzes,  but  merely  shoots  out  a 
small  flame.  When  Electric  Squibs  are  used,  the  charge  of  blast- 
ing powder  can  be  ignited  in  the  center,  giving  a  little  quicker  and 
stronger  action,  and  insuring  the  explosion  of  the  entire  charge 
before  any  of  the  surrounding  material  can  fall  and  cut  off  a 
portion  of  it.  The  bore  hole,  too,  can  be  tamped  solid,  leaving 
no  vent  for  a  partial  loss  of  the  strength  of  the  powder.  When 
the  entire  charge  is  exploded  at  once,  less  smoke  is  given  off  by 
the  explosive.  This,  with  the  elimination  of  smoke  from  burning 
safety  fuse,  results  in  purer  air,  making  it  possible  for  both  miners 
and  draught  animals  to  do  more  work. 

Other  advantages  in  the  use  of  Electric  Squibs  are 
that  when  more  than  one  shot  is  to  be  fired  all  of  the 
bore  holes  can  be  connected  in  series  and  fired  at  the 
same  instant,  resulting  in  a  very  considerable  saving  in 
both  powder  and  time,  and  shot  firers  can  cover  a  great 
deal  more  ground  than  when  using  fuse  or  miner's  squibs. 
It  is  much  safer  to  blast  with  Electric  Squibs  than 
with  fuse  or  miner's  squibs,  because  shots  are  not  fired 
until  everyone,  including  the  blaster,  is  a  safe  distance 
away,  and  because  danger  of  hang  fires  is  entirely  obviated. 
In  short,  the  advantages  gained  by  the  use  of  Elec- 
tric Squibs  may  be  summed  up  as  follows: 

More  work  from  a  given  amount  of  blasting  powder. 
Everybody  out  of  danger  before  the  shots  are  fired. 
No  waiting ;  the  firing  is  instantaneous. 
Any  number  of  shots  fired  simultaneously. 
No  fumes  from  burning  safety  fuse. 
Electric     ^  minimum  amount  of  smoke  from  the  blasting  powder. 

(Actual  'n  connectmg  UP  Electric  Squibs  for  firing,  the  wires, 

Size)     where  joined,  should  be  clean  and  bright.      Connections 

24 


should  be  made  in  series  in  the  same  manner  as  Victor  Electric 
Fuzes.     (See  illustration  on  page  6.) 

Electric  Squibs  require  the  same  storage  conditions  as 
Electric  Fuzes,  and  although  they  cannot  be  exploded  by  shock 
or  concussion  like  electric  fuzes,  they  must  be  handled  just  as 
carefully,  for  their  construction  is  necessarily  delicate  and  they 
can  be  easily  broken  by  rough  handling. 

They  are  manufac- 
tured with  4  feet,  5  feet,  6 
feet,  8  feet,  10  feet  and  12 
feet  copper  or  iron  wires. 
Those  with  iron  wires  are 
somewhat  less  expensive, 
but  require  a  stronger  elec- 
tric current  to  explode  them, 
because  of  the  inferior  con- 
ductivity of  iron  as  com- 
pared with  copper  wire. 
They  are  also  more  easily 
affected  by  moisture.  We  do  not  recommend  electric  squibs 
with  iron  wires  longer  than  8  feet,  nor  do  we  carry  them  in  stock. 

Electric  Squibs  are  packed  50  to  the  carton  and  1 0  cartons 
to  the  case.  Gross  and  net  weights  of  cases  are  as  follows : 


Quantity 

Length 

Gross  Wt. 

Net  Weight 
(In  Cartons) 

Outside  Dimensions  of  Cases 

500 

4' 

25    IBs. 

17K  Ibs. 

22"  x   9y2'  x9^" 

500 

5' 

27^" 

20         " 

22"  x   9y2f  x9y2" 

500 

6' 

31      " 

23y2    •• 

22"  x   9^'x9^" 

500 

8' 

39      " 

30       " 

22"  x  \\y2'  x9y2" 

500 

10' 

44      " 

33       " 

22"  x  \\y2f  x9y2" 

500 

12' 

54      " 

43X    " 

22"  x  15^'  x9^" 

25 


u 


u 


Reliable"  Blasting  Machines 
Pull  Up"  Blasting  Machines 


'Reliable  "  or  "U.  5.  Standard 
(Push  Down) 


'Pull  Up" 


28 


Blasting  Machines 

HE  DU  PONT  COMPANY  manufactures  two 
different  styles  of  blasting  machines,  but  these  are 
designed  on  the  same  general  principle.  They 
are: 

"Reliable "or  " U. S. Standard"  (Push  Down) 
" Pull  Up" 


The  "  Reliable  "  or  "  U.  S.  Standard  "*  Push  Down  Blasting 
Machine  is  manufactured  in  two  sizes  as  follows : 


Capacity     .    .    . 
Dimensions     .    . 
Net  Weight    .    . 
Weight,    Boxed 
for  Shipment  . 


No.  2 
(2  Posts  only) 

.  1  to  10  Electric  Fuzes. 
.  7"x8"x  14". 
.  20  Ibs. 

.  25  Ibs. 


No.  3 

(2    Posts,  unless  spec- 
ially ordered  with  3 

Posts) 

1  to  30  Electric  Fuzes. 
7"x  10"  x  18". 
25  Ibs. 

30  Ibs. 


U.  S.  Standard  Blasting  Machines  are  manufactured  in  No.  3  size  only. 

34 


16 


In  the  accompanying  illustration,  the  parts  marked  8  and  9 
are  field  magnets,  which  are  energized  by  the  current  from  the 
revolving  armature  1 6.  The  teeth  of  the  armature  pinion  engage 
with  the  rack  bar  1,  and  by  clutching  also  engage  with  the 
armature  shaft  on  the  downward  stroke  (only)  of  the  rack  bar. 


4  is  the  contact  spring,  which,  when  struck  by  the  bottom  of  the 
descending  rack  bar,  breaks  the  contact  between  two  small  plati- 
num bearings,  one  on  the  upper  face  of  the  contact  spring  and  the 
other  on  the  under  side  of  the  bridge  5,  and  in  this  way  throws 
the  entire  current  through  the  "outside"  circuit,  that  is,  leading 
wire,  electric  fuzes  and  connecting  wire ;  1 5  is  the  commutator. 
To  operate  the  push  down  blasting  machine,  lift  up  the 
rack  bar  by  the  handle  34  to  its  full  extent,  and  with  one  quick, 
hard  stroke  push  it  down  to  the  bottom  of  the  box  with  a  solid 
thud.  As  the  rack  bar  approaches  the  bottom,  it  becomes  more 
difficult  to  operate,  because  of  the  "  building  up "  of  the  blasting 
machine ;  but  the  speed  of  the  thrust  should  not  be  diminished, 
because  the  finish  of  the  operation  is  just  as  important  as  the 
start.  Do  not  be  afraid  of  pushing  the  rack  bar  down  too  hard. 
The  machine  is  built  to  stand  it,  and  this  is  the  only  way  to  use 
it  successfully. 


30 


ra 


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•^-•S 


31 


"Pull  Up"   Blasting  Machines  are  manufactured  in  No.  5 

size  only,  as  follows: 

No.  5 

(3  Posts  only) 
Capacity.    .    .    .    .    .    i  ••••*    .    ..-.    .. ' .    ...    .    .    '•    •    •    •    .  1  to  1 00  Electric  Fuzes. 

Dimensions .,..;............  12"  x  14"  x  23". 

Net  Weight      ......    ...... 50lbs. 

Weight,  Boxed  for  Shipment 65  Ibs. 


8  and  9  are  the  field  magnets  which  are  energized  by  current 
from  the  revolving  armature  1 6.  Motion  is  given  to  this  by  the 
upward  stroke  of  the  rack  bar  1  operating  on  the  crank  52  and 
the  train  of  gears  40  and  48.  The  quicker  the  upward  move- 
ment of  the  handle  36,  the  faster  the  armature  pinion  1 8  is  made 
to  revolve,  and  consequently  the  greater  the  current  generated. 
At  the  end  of  the  upward  stroke  the  impact  of  the  arm  61 
against  the  contact  spring  4  causes  the  circuit  to  be  broken 
between  it  and  the  bearing  point  of  the  contact  screw  6.  The 
current  is,  therefore,  at  that  instant  thrown  into,  and  causes  the 
firing  of  the  electric  fuzes. 

To  operate  the  "pull  up"  blasting  machine:  Stand  with 
each  foot  planted  firmly  on  the  flanges  on  either  side  of  the  bottom 
of  the  blasting  machine  and  pull  up  the  rack  bar  to  its  full  extent 
by  the  handle  with  a  quick,  hard  jerk.  As  the  limit  of  the  pull 
is  approached,  the  operation  becomes  more  difficult,  owing  to  the 
"building  up'*  of  the  blasting  machine;  but  the  speed  should  not 

32 


33 


be  diminished,  because  the  finish  of  the  stroke  is  just  as  important 
as  the  start.  Try  to  jerk  the  rack  bar  out  of  the  top  of  the 
blasting  machine.  A  half  hearted  attempt  to  operate  this  blasting 
machine  may  result  in  a  failure. 

The  capacity  of  three  post  blasting  machines  is  increased 
about  50  per  cent,  over  that  given  in  the  preceding  tables,  when 


Three  Post  Blasting  Machine  Connected  with 
Two  Leading  Wires 


Three  Post  Blasting  Machine,   Connected  with 
Three  Leading  Wires 

a  third  leading  wire  is  run  from  the  middle  binding  post,  and 
connected  to  the  middle  of  the  blasting  circuit,  the  leading  wires 
from  the  two  outside  binding  posts  being  connected  to  the  first 
and  last  electric  fuzes  in  the  circuit.  When  only  two  leading 
wires  are  used  with  the  three  post  machine,  they  must  be  con- 
nected to  the  middle  binding  post  and  either  one  of  the  outside 
binding  posts,  but  never  to  the  two  outside  binding  posts. 


34 


Our  blasting  machines  are  strongly  made,  and  will  stand  with 
little  deterioration  the  treatment  to  which  it  is  necessary  to  subject 
them.  Their  mechanism,  though  designed  as  simply  as  possible, 
is  more  or  less  complicated  and  delicate,  and  although  they  will 
withstand  the  usage  to  which  it  is  necessary  to  put  them,  they 
must  be  treated  with  at  least  some  consideration.  There  can  be 
no  possible  excuse  for  throwing  a  blasting  machine  about,  or 
permitting  it  to  remain  exposed  to  wet  weather  or  lying  in  the 
mud.  When  a  blasting  machine  is  treated  in  this  way,  its  life 
will  be  short  and  its  usefulness  limited. 

Remember  that  good  care  will  prolong  the  usefulness  of  the 
blasting  machine,  will  reduce  the  necessity  for  repairs  and  will  help 
to  maintain  its  efficiency.  The  bearings  and  gearings  should  be 
lightly  oiled  occasionally,  but  on  the  commutator,  which  is  the 
small  copper  covered  wheel  on  the  end  of  the  armature  shaft 
(see  1  5  in  illustration  on  pages  3 1  and  33),  use  a  little  graphite, 
but  never  use  oil.  See  that  the  two  slots  cut  in  the  copper  part 
of  the  commutator  are  clean,  and  with  no  particle  of  metal  or  any- 
thing else  in  them  which  might  cause  a  short  circuit.  Keep  the 
copper  brushes  (see  20  in  illustration  on  pages  3 1  and  33)  clean, 
and  see  that  they  bear  firmly  on  the  commutator.  Keep  the 
circuit  breaking  contacts  clean  and  bright. 

When  a  blasting  machine  is  not  in  use,  store  it  in  a  dry  and 
comparatively  cool  place ;  not  in  a  leaky  tool  box  or  on  top  of 
a  boiler. 

Every  blasting  machine  is  tested  thoroughly  before  leaving 
the  works,  and  if  a  new  one  does  not  give  satisfactory  results  when 
received,  it  may  have  been  injured  by  rough  handling  during 
transportation. 

The  parts  of  these  blasting  machines  are  all  standard, 
and  when  worn  out  or  broken  can  be  replaced  at  a  small  cost. 
When  ordering,  give  the  style  and  number  of  the  blasting  machine 
in  which  they  are  used,  as  well  as  the  number  of  the  part  as 
shown  in  illustrations  on  pages  31  and  33.  Do  not  return  a 
blasting  machine  to  us  to  be  repaired  without  first  securing 
proper  shipping  directions  from  our  nearest  branch  office,  a  list  of 
which  is  given  on  the  back  of  this  catalogue. 

35 


Connecting  Wire 
Leading  Wire 
Leading  Wire  Reel 


Connecting  Wire 

ONNECTING  WIRE  is  insulated  copper  wire 
(No.  20  Brown  &  Sharpe  gauge).  It  is  put  up 
in  1  pound  and  2  pound  spools.  A  1  pound 
spool  is  3  inches  in  diameter,  4  inches  long  and 
holds  about  2 1 0  feet  of  wire.  A  2  pound  spool 
is  3  inches  in  diameter,  5  j4  inches  long  and  holds 
about  420  feet  of  wire. 
Connecting  Wire  is  used  to  join  the  wires  of 
the  electric  fuzes  together,  when  they  are  not  long 
enough  to  reach  between  the  adjoining  bore  holes. 
The  ends  of  the  connecting  wire  must  be  scraped 
bright  before  connections  are  made,  and  the  joints 
should  not  be  permitted  to  lie  in  water  or  on  wet 
ground.  If  this  cannot  be  prevented,  the  joint  should  Connecting  Wire 
be  covered  with  insulating  tape. 

No.  21  (Brown  &  Sharpe  gauge)  Insulated  Copper  Wire 
is  also  used  for  connecting  wire,  but  we  do  not  recommend  it 
because  we  consider  it  too  small  for  best  results. 

A  1  pound  spool  of  No.  21  Connecting  Wire  holds  about 
260  feet  and  a  2  pound  spool  about  520  feet. 


Leading  Wire 

The  wire  commonly  used  for  connecting  electric  fuzes  to 
the  blasting    machine    is    known  as  Leading  Wire.     It 


is    m- 


39 


sulated  copper  wire  (No.    14  Brown  &  Sharpe  gauge)  and  is 
furnished  in  coils  of  the  following  lengths  and  weights: 

Ibs. 


200  ft. 
250  " 
300  " 

500  " 


about  4 

"     5 

"     5.8 
"     9.6 


Duplex  Leading  Wire  is  made 
by  binding  together  two  insulated  cop- 
Leading  Wire  per  wires  with  an  outside  insulation, 

giving  it  the  effect  of  a  single  cable.     It  is  somewhat  higher  in 
price,  but  generally  more  convenient  than  single  leading  wire. 

It  weighs  approximately  twice  as  much  as  the  same  length 
of  single  leading  wire,  and  can  be  had  in  coils  of  the  same  length. 


\  v 

^  . 


Duplex  Leading  Wire  (Actual  Size) 


Leading  Wire  Reels 

A  Leading  Wire  Reel  is  very  useful,  and  will  soon  pay  for 
itself  by  keeping  the  leading  wire  in  good  condition  and  in  saving 
time.  It  weighs  empty  about  1 6  pounds,  and  is  1  1  /^  inches 
high,  18  inches 
long  including 
handle,  and  has 
a  maximum  ca- 
pacity of  800 
feet  (400  feet 
double)  of  No. 
14  (Brown  & 
Sharpe  gauge) 

insulated  wire.  Leading  Wire  Reel 


40 


Galvanometers 


Galvanometers 

HIS  instrument  comprises  a  galvanometer  and  a 
battery  (Fig.  1,  page  44),  mounted  in  a  suitable 
case  of  metal  and  hard  rubber  (Fig.  2),  which 
in  turn  is  contained  in  an  outer  case  of  sole  leather 
equipped  with  a  strong  sling  strap*  (Fig.  3);  the 
whole  being  designed  with  a  thorough  knowledge 
of  the  conditions  prevailing  on  the  work  where 
electric  blasting  is  done,  and  with  a  view  to  pro- 
ducing an  instrument  strong  enough  to  withstand  such  conditions 

and  at  the  same  time  retain  sufficient 

delicacy  to  make  reliable  tests. 

The  Galvanometer  is  of  the 

upright    type, 

with  a  magnetic 

needle    of    such 

design   that    the 

pointer  is  held  at 

the  starting  point 

of  the  scale  by 

gravity    alone, 

thus   eliminating 

the  necessity  of 

holding   the    in- 
strument   with 

any  reference  to 

a  north  and  south 

position,  or  of  using  a  permanent  magnetic  field  or  springs  of  any 

kind  in  its  construction.     The  only  precaution  as  to  position  is 

*  Leather  galvanometer  cases  are  also  made  with  a  compartment  for  the  Du  Pont  Rheostat. 


Fig.  2  Fig.  3 

Du  Pont  Galvanometer 

Dimensions  (including  case) 2n  x  3n  x 

Weight  (including  case  and  strap) /  Ib. 


43 


that  it  be  held  reasonably  level.  The  scale  (see  cut,  Fig.  4) 
is  graduated  in  a  reverse  direction,  and  the  units  thereon  represent 
ohms  resistance  in  the  outer  circuit.  The  idea  is  to  not  merely 
show  whether  a  given  circuit  is  "open"  or  "closed,"  but  to  give 
an  approximate  idea  of  the  resistance  of  such  circuit  within  the 
limitations  of  an  instrument  of  this  type.  For  instance,  if  the 
poles  of  the  instrument  be  Fig.  4 

short  circuited  by  means  of  a 
thick  piece  of  wire  of  practi- 
cally no  resistance,  the  indicator 
needle  or  pointer  will  go  across 
the  entire  scale  and  stop  at 
zero.  If  the  outer  circuit  has 
a  resistance  of  64  ohms, 
the  needle  will  not  be 
deflected  so  far,  but  will 
stop  at  64,  and  so  on. 
Changes  in  the  strength 
of  the  battery  cell  will, 
of  course,  introduce  errors 
into  these  readings,  but 
by  taking  occasional  trial 
readings  through  known 
resistances  (such  as  those  pro- 
vided in  the  Du  Pont  Rheostat) 
and  replacing  the  battery  cell 
when  it  becomes  weak,  these 
errors  will  be  minimized.  The 
information  given  by  this  instru- 
ment will  be  found  of  great  value, 
in  testing  a  blasting  circuit,  for,  rough  as  the  resistance  measure- 
ments may  be,  they  serve  to  detect  short  circuits  as  well  as  breaks, 
and  are  a  help  in  testing  single  electric  fuzes,  both  before  and 
after  loading  them  into  the  bore  holes. 

The    battery  cell  (Fig.   5)  is    of  a  kind    selected   by  us 
after  a  long  series  of  experiments.     While  of  long  life  and  of 


Fig.  1 
Parts  of  Du  Pont  Galvanometer 


44 


great  constancy,  it  is  a  very  weak  battery  cell,  and  the  current 
which  is  sent  through  an  electric  fuze  when  making  a  test  with 
the  assembled  instrument  is  less  than  one-tenth  of  the  strength 
required  to  explode  it.  The  length  of  time  a  battery  cell  will 
last  depends,  of  course,  upon  how  frequently  it  is  used  and  how 
long  the  current  is  allowed  to  flow  in  making  each  test.  When 
properly  used,  one  cell  is  sufficient  for  several  thousand  tests. 
The  simple  form  of  connector  enables  the  user  to  replace  the 
exhausted  cell  with  a  new  one  with  but  little  trouble.  The  bat- 
tery cell  is  very  small  and  light  and  can  be  sent  by  mail. 

To  renew  the  battery  cell,  take  out  the  four  screws  in  the 
sides  of  the  metal  case.  The  working  parts  can  then  be  lifted 
out  entire,  being  all  suspended  from  the  hard  rubber  top.  The 
exhausted  battery  cell  is  then  removed  by  pulling  downward, 
when  its  two  poles  will  come  out  of  the  split  bushings,  leaving  it 
free.  The  new  battery  cell  is  replaced  by  simply  pushing  its 
two  poles  into  the  split  bushings,  just  as  the  old  one  was  con- 
nected. The  only  precaution  necessary  is  to  be  sure  the  — |- 
and  —  poles  are  connected  to  the  corresponding  bushings  so 
marked. 

In  use,  the  instrument  in  its  leather  case  is  carried  by  the 
blaster  at  his  side,  slung  from  the  strap  which  passes  over  his 
opposite  shoulder,  in  the  same  manner  as  a  field  glass  is  carried. 
To  make  a  test,  it  is  only  necessary  to  touch  the  ends  of  the  two 
wires  to  the  two  binding  posts,  when  the  indicator  will  immediately 
move  over  the  scale  and,  after  a  few  oscillations,  stop  at  a 
position  corresponding  with  the  resistance  of  the  circuit,  which 
can  be  read  from  the  scale.  On  pages  50  and  5 1  will  be  found 
a  table  giving  the  average  resistance  of  electric  blasting  cir- 
cuits. If  the  test  indicates  a  resistance  greatly  at  variance  with 
what  it  should  be,  the  blaster  knows  at  once  that  something  is 
wrong.  Breaks  are  quickly  located,  merely  by  following  the 
simple  instructions  given  later.  The  instrument  and  the  methods 
of  using  it  are  such  as  apply  to  the  requirements  of  the  practical 
blaster,  as  distinguished  from  the  trained  electrician,  whose  finer 

45 


instruments  and  methods  would  be  at  a  disadvantage  under  the 
conditions  prevailing  on  the  ordinary  electric  blasting  job. 

We  commend  the  instrument  to  our  customers  because  it 
is  a  convenience  and  a  time  saver,  and  also  because  the  more 
exact  methods  which  it  makes  possible  not  only  enable  them  to 
secure  better  execution  from  our  goods,  but  most  important  of 
all,  these  exact  methods  minimize  danger  and  lessen  the  risk  of 
accidents. 

Testing  the  Galvanometer 

Before  using,  test  the  Galvanometer  by  placing  a  short 
piece  of  thick  copper  wire  across  its  two  binding  posts.  The 
wire  having  almost  no  resistance,  the  needle  should  be  deflected 
to  its  widest  limit,  marked  zero  on  the  scale.  If  it  does  not  move 
or  go  as  far  as  zero,  the  battery  cell  is  exhausted  or  weakened. 
Other  useful  tests,  giving  practice  in  the  use  of  the  instrument,  can 
be  made  by  means  of  the  Du  Pont  Rheostat  (see  cut,  page  55), 
with  which  known  resistances  can  be  tried  on  the  Galvanometer, 
and  its  reading  for  those  resistances  verified. 

Table  of  Resistances  of  Rheostat  in  Ohms 

The  resistances  furnished  between  the  different  posts  of  the 
Rheostat  are  as  follows: 

Between  1  and  2     ....  16  ohms 


II 

? 

3  

32  ' 

. 

3 

4  

....     64  « 

« 

4 

5  

.  .  .  .     80  ' 

. 

5 

6  

128  ' 

< 

1 

3  ... 

4ft  ' 

. 

1 

4  

112 

« 

1 

5  

192 

« 

1 

6  

320 

. 

2 

4  

....     96 

4 

?, 

5  

176 

. 

?, 

6  

304 

. 

3 

5  

.  .  .      144 

« 

3 

6  

272  ' 

' 

4 

6  .       .  •  •  • 

.  208  ' 

46 


Fig.  7 


47 


Directions  for  Using 

The  operation  of  the  instrument  is  as  follows:  When  a 
passageway  ("circuit")  is  offered,  so  that  the  electric  current 
can  pass  from  one  binding  post  to  the  other,  the  current 
from  the  battery  cell  flows  through  this  circuit,  traversing  the 
Galvanometer  coil  on  the  way,  and  causing  its  needle  to  be 
deflected.  The  amount  of  the  deflection  is  greater  when  the  circuit 
has  little  resistance,  and  less  when  the  circuit  has  greater  resistance. 

Although  the  Galvanometer  is  comparatively  simple  in  design, 
and  as  substantially  made  as  possible  for  such  an  instrument, 
some  of  the  parts  are  necessarily  of  delicate  construction.  It 
should,  therefore,  be  handled  carefully  and  kept  perfectly  dry. 

To  Test  a  Circuit 

To  test  a  circuit  with  the  Galvanometer,  connect  or 
touch  the  leading  wires  to  its  two  binding  posts,  after  everything 
is  made  ready  to  fire.  If  the  circuit  is  perfect,  it  will  have  the 
right  resistance  (see  pages  50  and  5 1 ),  and  the  needle  will  move 
to  the  corresponding  number  on  the  dial.  If  it  moves  too  far,  it 
shows  that  there  is  a  "short  circuit"  or  "leak,"  and  that  part 
of  the  electric  current  is  not  going  through  all  the  electric  fuzes, 
but  is  escaping  across  some  easier  circuit.  If  the  needle  does  not 
move  at  all,  or  not  as  far  as  it  should,  there  is  a  break  in  the 
circuit,  or  some  high  resistance  like  a  bad  joint. 

To  Locate  a  Break 

To  locate  a  break,  make  sure  that  the  ends  of  the  leading 
wires,  which  you  would  attach  to  the  blasting  machine,  are 
separated  and  not  touching  anything  (see  Fig.  7,  page  47).  Carry 
the  Galvanometer  with  you  to  the  loaded  bore  holes.  Attach  a 
piece  of  connecting  wire  "N"  to  one  binding  post  "K"  of  the 
Galvanometer,  long  enough  for  you  to  fasten  its  other  end  to  the 
joint  "D,"  and  still  have  slack  enough  to  reach  each  of  the  other 
bore  holes.  Now  touch  the  binding  post  "L"  of  the  Galva- 
nometer to  the  joint  "C."  If  the  Galvanometer  now  shows 
circuit,  while  it  did  not  when  the  test  was  made  from  the  other 

48 


end  of  the  leading  wires,  the  break  is  in  the  leading  wires.  If  it 
does  not  show  circuit,  find  the  break  in  the  electric  fuze  circuit, 
by  touching  the  binding  post  "  L"  (or  a  short  piece  of  wire  "M" 
connecting  with  binding  post  "L,"  whichever  is  more  convenient) 
to  each  of  the  bare  joints  "E,"  "F,"  "G,"  and  "H"  in  succession. 
As  long  as  you  are  "inside"  the  break,  these  contacts  will  cause 
the  needle  to  be  deflected.  As  soon  as  you  get  beyond  the  break, 
or  point  of  high  resistance,  you  get  either  very  slight  deflection  or 
none  at  all.  In  this  way  the  trouble  can  quickly  be  traced  to  the 
particular  electric  fuze  in  which  the  break  exists.  For  instance, 
if  the  electric  fuze  wire  in  bore  hole  No.  3  is  broken,  you  get  a 
deflection  when  "L"  or  "M"  is  touched  to  "F,"  but  none  on 
touching  "G" ;  showing  that  the  break  is  between  "F"  and  "G." 

Single  electric  fuzes  can  also  be  tested,  both  before  and 
after  putting  them  in  the  bore  hole,  simply  by  touching  the  ends 
of  the  electric  fuze  wires  (scraped  clean)  to  the  two  binding  posts. 
(See  Caution,  page  52.)  The  resistance  of  one  electric  fuze  is 
so  small  that  it  should  cause  a  wide  deflection. 

Hold  the  instrument  with  the  dial  level.  If  the  needle 
does  not  move  at  all  when  a  test  is  made,  jar  it  slightly  to  make 
sure  it  is  not  stuck. 

Renew  the  battery  cell  in  the  Galvanometer  when  it  is 
exhausted,  and  test  the  Galvanometer  frequently  to  make  sure  it 
is  in  good  working  order. 

How  to  Use  the  Tables  on  Pages  50  and  51 

The  numbers  above  the  double  lines  at  the  head  of  the 
columns  refer  to  the  length  of  the  wires  of  the  electric  fuzes 
used.  Select  whatever  column  refers  to  the  length  you  are  using, 
and,  beginning  at  the  top,  follow  it  down  to  the  number  of  electric 
fuzes  in  the  circuit  to  be  tested  as  shown  in  the  first  column. 
For  instance,  if  you  have  three  1 2  foot  electric  fuzes,  the  resist- 
ance should  be  3.7  ohms.  If  you  have  fifty  12  foot  electric 
fuzes,  the  resistance  should  be  62.2  ohms,  and  so  on.  These 
resistances  are  only  approximate,  but  they  are  sufficiently  close 
to  give  useful  information. 

49 


Table  of  Resistances  of  Blasting  Circuits  in   Ohms 


No.  of 

Flprtrir 

LENGTH    OF    FUZE    WIRES    IN    FEET 

Uticcinc 
Fuzes  in 
Circuit 

2 

4 

6 

8 

10 

12 

14 

16 

18 

20 

22 

24 

26 

28 

1 

0.9 

1.0 

l.i 

1.1 

1.2 

1.2 

1.3     1.4 

1.4 

1.5 

1.6 

1.6 

1.7 

1.8 

2 

1.9 

2.0 

2.1 

2.2 

2.4 

2.5 

2.6 

2.7 

2.9 

3.0 

3.1 

3.3 

3.4 

3.5 

3 

2.8 

3.0 

3.2 

3.3 

3.5 

3.7 

3.9 

4.1 

4.3 

4.5 

4.7 

4.9 

5.1 

5.2 

4 

3.7 

4.0 

4.2 

4.5 

4.7 

5.0 

5.2 

5.5 

5.7 

6.0 

6.3 

6.5 

6.8 

7.0 

5 

4.6 

4.9 

5  3 

5.6 

5.9 

6.2 

6.5 

6.9 

7.2 

7.5 

7.8 

8.1 

8.5 

8.8 

6 

5.5 

5.9 

6.3 

6.7 

7.1 

7.5 

7.8 

8.2 

8.6 

9.0 

9.4 

9.8 

10.1 

10.5 

7 

6.5 

6.9 

7.4 

7.8 

8.3 

8.7 

9.1 

9.6 

10.0 

10.5 

10.9 

11.4 

11.8 

12.2 

8 

7.4 

7.9 

8.4 

8.9 

9.4 

9.9 

10.5 

11.0 

11.5 

12.0 

12.5 

13.0 

13.5 

14.0 

9 

8.3 

8.9 

9.5 

10.0 

10.6 

11.2 

11.8 

12.3 

12.9 

13.5 

14.1 

14.6 

15.2 

15.8 

10 

9.2 

9.9 

10.5 

11.1 

11.8 

12.4 

13.1 

13.7 

14.4 

15.0 

15.6 

16.3 

16.9 

17.5 

11 

10.2 

10.9 

11.6 

12.3 

13.0 

13.7 

14.4 

15.1 

15.8 

16.5 

17.2 

17.9 

18.6 

19.2 

12 

11.1 

11.8 

12.6 

13.4 

14.1 

14.9 

15.7 

16.5 

17.2 

18.0 

18.8 

19.5 

20.3 

21.0 

13 

12.0 

12.8 

13.7 

14.5 

15.3 

16.2 

17.0 

17.8 

18.7 

19.5 

20.3 

21.2 

22.0 

22.8 

14 

12.9  13.8 

14.7 

15.6 

16.5 

17.4 

18.3 

19.2 

20.1 

21.0 

21.9 

22.8 

23.7  24.6 

15 

13.8   14.8 

15.8 

16.7 

17.7 

18.6 

19.6 

20.6 

21.5 

22.5 

23.4 

24.4 

25.4   26.3 

16 

14.8  15.8 

16.8 

17.8 

18.9 

19.9 

20.9 

21.9 

23.0 

24.0 

25.0 

26.0 

27.1 

28.0 

17 

15.7 

16.8 

17.9 

19.0 

20.0 

21.1 

22.2 

23.3 

24.4 

25.5 

26.6 

27.7 

28.8 

29.8 

18 

16.6 

17.8 

18.9 

20.1 

21.2 

22.4 

23.5 

24.7 

25.8 

27.0 

28.1 

29.3 

30.4 

31.6 

19 

17.5 

18.8 

20.0 

21.2 

22.4 

236 

24.8 

26.0 

27.3 

28.5 

29.7 

30.9 

32.1 

33.3 

20 

18.5 

19.7 

21.0 

22.3 

23.6 

24.9 

26.1 

274 

28.7 

30.0  31.3 

32.5 

33.8 

35.0 

21 

19.4 

20.7 

22.1 

23.4 

24.8 

2tU 

27.4 

28.8 

30.1 

31.5 

32.8 

34.2 

35.5 

36.8 

22 

20.3 

21.7 

23.1 

24.5 

25.9 

27.4 

28.8 

30.2 

31.6 

33.0 

34.4 

35.8 

37.2 

38.6 

23 

21.2 

22.7 

24.2 

25.6 

27.1 

28.6 

30.1 

31.5 

33.0 

345 

35.9 

37.4 

38.9 

40.3 

24 

22.2 

23.7 

25.2 

26.8 

28.3 

29.8 

31.4 

32.9 

34.4 

36.0 

37.5 

39.1 

40.6 

42.0 

25 

23.1 

24.7 

26.3 

27.9 

29.5 

31.1 

32.7 

34.3 

35.9 

37.5 

39.1 

40.7 

42.3 

43.9 

26 

24.0 

25.7 

27.3 

29.0 

30.7 

32.3 

34.0 

35.6 

37.3 

39.0 

40.6 

42.3 

44.0 

45.6 

27 

24.9 

26.6 

28.4 

30.1 

31.8 

33.6 

35.3 

37.0 

38.7 

40.5 

42.2 

43.9 

45.7 

47.4 

28 

25.8 

27.6 

29.4 

31.2 

33.0 

34.8 

36.6 

38.4 

40.2 

42.0 

43.8 

45.6 

47.3 

49.1 

29 

26.8 

28.6 

30.5 

32.3 

34.2 

36.1 

37.9 

39.8 

41.6 

43.5 

45.3 

47.2 

49.0 

50.9 

30 

27.7 

29.6 

31.5 

33.5 

35.4 

37.3 

39.2 

41.1 

43.1 

45.0 

46.9 

48.8 

50.7 

52.6 

31 

28.6 

30.6 

32.6 

34.6 

36.6 

38.5 

40.5 

42.5 

44.5 

46.5 

48.5 

50.4 

52.4 

54.4 

32 

29.5 

31.6 

33.6 

35.7 

37.7 

39.8 

41.8 

43.9 

45.9 

48.0 

50.0 

52.1 

54.1 

56.1 

33 

30.5 

32.6 

34.7 

36.8 

38.9 

41.0 

43.1 

45.2 

47.4 

49.5 

51.6 

53.7 

55.8 

57.9 

34 

31.4 

33.6 

35.7 

37.9 

40.1 

42.3 

44.4 

46.6 

48.8 

51.0 

53.1 

55.3 

57.5 

596 

35 

32.3 

34.5 

36.8 

39.0 

41.3 

43.5 

45.7 

48.0 

50.2 

52.5 

54.7 

56.9 

59.21  61.4 

36 

33.2 

35.5 

37.8 

40.1 

42.4 

44.8 

47.1 

49.4 

51.7 

54.0 

56.3 

58.6 

60.9 

63  1 

37 

34.2 

36.5 

38.9 

41.3 

43.6 

46.0 

48.4 

50.7 

53.1 

55.5 

57.8 

60.2 

62.6 

64.9 

38 

35.1 

37.5 

39.9 

42.4 

44.8 

47.2 

49.7 

52.1 

54.5 

57.0 

59.4 

61.8 

64.3 

66.7 

39 

36.0 

38.5 

41.0 

43.5 

46.0 

48.5 

51.0 

53.5 

56.0 

58.5 

61.0 

63.5 

65.9 

68.4 

40 

36.9 

39.5 

42.0 

44.6 

47.2 

49.7 

52.3 

54.8 

57.4 

60.0 

62.5 

65.1 

67.6 

70.2 

41 

37.8 

40.5 

43.1 

45.7 

48.3 

51  0 

536 

56.2 

58.8 

61  5 

64.1 

66.7 

69.3 

71.9 

42 

38.8 

41.5 

44.1 

46.8 

49.5 

52.2 

549 

57.6 

60.3 

63.0 

65.6 

68.3 

71.0 

73.7 

43 

39.7 

42.4 

45.2 

47.9 

50.7 

53.5 

56.2 

59.0 

61.7 

64.5 

67.2 

70.0 

72.7 

75.4 

44 

40.6 

43.4 

46.2 

49.1 

51.9 

54.7 

57.5 

60.3 

63.1 

66.0 

68.8 

71.6 

74.4 

77.1 

45 

41.5 

44.4 

47.3 

50.2 

53.1 

55.9 

58.8 

61.7 

64.6 

67.5 

70.3 

73.2 

76.1 

78.9 

46 

42.5 

45.4 

48.3 

51.3 

54.2 

57.2 

60.1 

63.1 

66.0 

69.0 

71.9 

74.8 

77.8 

80.7 

47 

43.4 

46.4 

49.4 

52.4 

55.4 

58.4 

61.4 

64.4 

67.4 

70.5 

73.5 

76.5 

79.5 

82.4 

48 

44.3 

47.4 

50.4 

53.5 

56.6 

59.7 

62.7 

65.8 

68.9 

72.0 

75.0 

78.1 

81.2 

84.2 

49 

45.2 

48.4 

51.5 

54.6 

57.8 

60.9 

64.0 

67.2 

70.3 

73.5 

76.6 

79.7 

82.9 

85.9 

50 

46.2 

49.4 

526 

55.8 

59.0 

62.2 

65.4 

68.6 

71.8 

75.0 

78.2 

81.4 

84.6 

87.7 

Decimals  smaller  than  0.1    ohm  eliminated 

50 


Table  of  Resistances  of  Blasting  Circuits  in   Ohms 


No.  of 
Electric 
Fuzes  in 
Circuit 

LENGTH    OF    FUZE   WIRES    IN    FEET 

30 

32 

34 

36 

38 

40 

42 

44 

46 

48 

50 

1 

1.8 

1.9 

1.9 

2.0 

2.1 

2.1 

2.2 

2.3 

2.3 

2.4 

2.5 

2 

3.6 

3.8 

3.9 

4.0 

4.2 

4.3 

4.4 

4.5 

4.7 

4.8 

4.9 

3 

5.5 

5.6 

5.8 

6.0 

6.2 

6.4 

6.6 

6.8 

7.0 

7.2 

7.4 

4 

7.3 

7.5 

7.8 

8.0 

8.3 

8.6 

8.8 

9.1 

9.3 

9.6 

9.8 

5 

9.1 

9.4 

9.7 

10.1 

10.4 

10.7 

11.0 

11.3 

11.7 

12.0 

12.3 

6 

10.9 

11.3 

11.7 

12.1 

12.5 

12.8 

13.2 

13.6 

14.0 

14.4 

14.8 

7 

12.7 

13.2 

13.6 

14.1 

14.5 

15.0 

15.4 

15.9 

16.3 

16.8 

17.2 

8 

14.6 

15.1 

15.6 

16.1 

16.6 

17.1 

17.6 

18.1 

18.7 

19.2 

19.7 

9 

163 

16.9 

17.5 

18.1 

18.7 

19.3 

19.8 

20.4 

21.0 

21.6 

22.1. 

10 

18.2 

18.8 

19.5 

20.1 

20.8 

21.4 

22.0 

22.7 

23.3 

24.0 

24.6 

11 

20.0 

20.7 

21.4 

22.1 

22.8 

23.5 

24.2 

24.9 

25.6 

26.3 

27.1 

12 

21.8 

22.6 

23.4 

24.1 

24.9 

25.7 

26.4 

27.2 

28.0 

28.7 

29.5 

13 

23.7 

24.4 

25.3 

26.1 

27.0 

27.8 

28.6 

29.5 

30.3 

31.1 

32.0 

14 

25.5 

26.3 

27.3 

28.2 

29.1 

29.9 

30.8 

31.7 

32.6 

33.5 

34.4 

15 

27.3 

28.2 

29.2 

30.2 

31.1 

32.1 

33.1 

34.0 

35.0 

35.9 

36.9 

16 

29.1 

30.1 

31.2      32.2 

33.2 

34.2 

35.3 

36.3 

37.3 

38.3 

39.3 

17 

30.9 

32.0 

33.1  i    34.2 

35.3 

36.4 

37.5 

38.5 

39.6 

40.7 

41.8 

18 

32.7 

33.9 

35.0      36  2 

37.4 

38.5 

39.7 

40.8 

42.0 

43.1 

44.3 

19 

34.6 

35.8 

37.0      38.2 

39.4 

40.6 

41.9 

43.1 

44.3 

45.5 

46.7 

20 

36.4 

37.7 

38.9      40.2 

41.5 

42.8 

44.1 

45.3 

46.6 

47.9 

49.2 

21 

38.2 

39.5 

40.9 

42.2 

43.6 

44.9 

46.3 

47.6 

49.0 

50.3 

51.6 

22 

40.0 

41.4 

42.8 

44.2 

45.7 

47.1 

48.5 

49.9 

51.3 

52.7 

54.1 

23 

41.9 

43.3 

44.8 

46.3 

47.7 

49.2 

50.7 

52.1 

53.6 

55.1 

56.6 

24 

43.7 

45.2 

46.7 

48.3 

49.8 

51.3 

52.9 

54.4 

55.9 

57.5 

59.0 

25 

45.5 

47.1     48.7 

50.3 

51.9 

53.5 

55.1 

56.7 

58.3 

59.9 

61.5 

26 

47.3 

49.0 

50.6 

52.3 

54.0 

55.6 

57.3 

58.9 

60.6 

62.3 

63.9 

27 

49.1 

50.9 

52.6 

54.3 

56.0 

57.8 

59.5 

61.2 

62.9 

64.7 

66.4 

28 

50.9 

52.7 

54.5 

56.3 

58.1 

59.9 

61.7 

63.5 

65.3 

67.1 

68.9 

29 

52.8 

54.6 

56.5 

58.3 

60.2 

62.0 

63.9 

65.7 

67  6  - 

69.5 

71.3 

30 

54.6 

56.5 

58.4 

60.3 

62.3 

64.2 

66.1 

68.0 

69.9 

71.9 

73.8 

31 

56.4 

58.4 

60.4 

62.3 

64.3 

66.3 

68.3 

70.3 

72.3 

74.2 

76.2 

32 

58.2 

60.3 

62.3 

64.4 

66.4 

68.4 

70.5 

72.5 

74.6 

76.6 

78.7 

33 

60.0 

62.1 

64.3 

66.4 

68.5 

70.6 

72.7 

74.8 

76.9 

79.0 

81.1 

34 

61.8 

64.0 

66.2 

68.4 

706 

72.7 

74.9 

77.1 

79.3 

81.4 

83.6 

35 

63.7 

65.9 

68.1 

70.4 

72.6 

74.9 

77.1 

79.4 

81.6 

83.8 

86.1 

36 

65.5 

67.8 

70.1 

72.4 

74.7 

77.0 

79.3 

81.6 

83.9 

86.2 

88.6 

37 

67.3 

69.7 

720 

74.4 

76.8 

79.1 

81,5 

83.9 

86.3 

88.6 

91.0 

38 

69.1 

71.6 

74.0 

70.4 

78.9 

81.3 

83.7  ,    86.1 

88.6 

91.0 

93.4 

39 

70.9 

73.4 

75  9 

78.4 

80.9 

83.4 

85.9 

88.4 

90.9 

93.4 

95.9 

40 

72.8 

-75.3 

77.9 

80.4 

83.0 

85.6 

88.1 

90.7 

93.2 

95.8 

98.4 

41 

74.6 

77.2 

79.8 

82.5 

85.1 

87.7 

90.3 

93.0 

95.6 

98.2 

100.8 

42 

76.4 

79.1 

81.8 

84.5 

87.2 

89.8 

92.5 

95.2 

97.9 

100.6 

103.3 

43 

78.2 

81.0 

83.7 

86.5 

89.2 

92.0 

94.7 

97.5 

100.2 

103.0 

105.7 

44 

80.0 

82.9 

85.7 

88.5 

91.3 

94  1 

96.9 

99.7 

102.6 

1054 

108.2 

45 

81.9 

84.7 

87.6 

90.5 

93.4 

96.3 

99.1 

102.0 

104.9 

107.8 

110.7 

46 

83.7 

86.6 

89.6 

92.5 

95.5 

98.4 

101.3 

104.3 

107.2 

110.2 

113.1 

47 

85.5 

88.5 

91.5 

94.5 

97.5 

100.5 

103.5 

106.5 

109.6 

112.6 

1156 

48 

87.3 

90.4 

93.5 

96.5 

99.6 

102.7 

105.7 

108.8 

111.9 

115.0 

118.0 

49 

89.1 

92.3 

95.4 

98.5 

101.7 

104.8 

108.0    111.1 

114.2 

117.4 

120.5 

50 

91.0 

94.2 

97.4 

100.6 

103.8 

107.0 

110.2    113.4 

116.6 

119.8 

123.0 

Decimals  smaller  than  0.1   ohm  eliminated 
51 


Caution 

The  question  is  often  asked  whether  it  is  absolutely  safe 
to  pass,  even  the  weak  testing  current,  of  this  Galvanometer 
through  a  single  electric  fuze.  The  only  answer  we  can  give 
is  that  while  we  test  many  thousands  of  electric  fuzes  every 
month,  by  passing  weak  electric  currents  through  them,  without 
accidents,  still  there  is  nothing  in  the  handling  of  explosives,  or 
electric  fuzes,  that  can  be  said  to  be  entirely  safe.  Those  who 
question  the  safety  of  testing  a  single  electric  fuze,  or  circuits 
containing  electric  fuzes,  in  the  manner  outlined  above  can  insure 
greater  safety  when  testing  a  single  electric  fuze,  by  placing  it  in 
a  short  piece  of  iron  pipe,  or  similar  receptacle,  so  that  its  acci- 
dental detonation  would  do  no  harm.  In  locating  breaks  in  a 
circuit  where  the  electric  fuzes  are  in  the  bore  holes,  the  tests  can 
be  made  from  a  safe  distance,  through  a  pair  of  leading  wires. 
The  latter  procedure  involves,  of  course,  the  disconnecting  of  the 
Galvanometer  from  the  ends  of  the  lead  wires,  and  a  trip  to  the 
loaded  bore  hole,  every  time  the  connections  are  changed  for  a 
new  test. 


52 


Rheostats 


Rheostats 

HE  purpose  of  a  Rheostat  is  to  provide  a  means 
of  ascertaining  the  capacity  of  a  Blasting  Machine 
in  an  inexpensive  way.  For  instance,  if  you  have 
a  blasting  machine  rated  as  capable  of  firing  ten 
electric  fuzes,  there  are  two  ways  in  which  its 
ability  to  do  this  may  be  proved :  First,  a  circuit 
of  ten  electric  fuzes  (Fig.  1 ,  page  56)  can  be  con- 
nected up,  and  the  attempt  made  to  fire  them  all; 
or,  second,  a  circuit  can  be 
prepared,  eliminating  nine  of 
the  ten  electric  fuzes,  and  re- 
placing them  with  an  equiva- 
lent resistance  (Fig.  2,  page 
56).  If  under  these  latter  cir- 
cumstances, the  single  electric 
fuze  can  be  fired,  it  is  presumptive  evidence  that  the  blasting 
machine  is  capable  of  firing  ten  electric  fuzes,  when  connected 
as  in  Fig.  1,  page  56,  provided  the  resistance  introduced  at  "R" 
(Fig.  2)  has  sufficient  surplus  to  offset  normal  variations  in  the 
sensitiveness  of  different  electric  fuzes  in  the  circuit. 

The  Rheostat  is  designed  to  furnish  this  artificial  resistance, 
which  replaces  the  electric  fuzes  included  within  the  dotted  lines 
(Fig.  1),  the  wires  "X"  and  "Y"  being  connected  with  the 
Rheostat  instead  of  with  the  nine  electric  fuzes  as  shown.  The 
internal  construction  of  the  Rheostat  is  shown  in  Fig.  3,  page  57. 
It  is  an  arrangement  of  coils  of  high  resistance  wire  of  a  certain 
length,  with  the  binding  posts  1  and  6  attached  to  its  ends,  and  the 
binding  posts  2,  3,  4  and  5  attached  to  it  at  intermediate  points. 
The  entire  length  of  the  resistance  wire  in  the  Rheostat  has  a 


Dimensions 
Weight      . 


55 


resistance  sufficient  to  represent  a  test  of  one  hundred  30  foot 
electric  fuzes,  with  the  leading  wire,  connecting  wire  and  all 
connections  in  the  blasting  circuit. 


It  will  be  noted  that  the  binding  posts  1 ,  2,  3, 4,  5  and  6  are 
not  attached  to  the  resistance  wire  at  equal  distances.  The  purpose 
of  this  is  to  afford  different  resistances  between  different  binding 

posts,  each  representing  a  test 
of  a  certain  number  of  electric 
fuzes.  If  the  wires  "X"  and 
"  Y"  (see  Fig.  2,  this  page,  and 
Fig.  4,  page  57)  are  attached 
to  binding  posts  1  and  2,  it 
represents  a  test  of  five  electric 
fuzes;  if  to  posts  2  and  3,  ten 
electric  fuzes;  to  posts  3  and 
4,  twenty  electric  fuzes;  or  to 
posts  4  and  5,  twenty-five 
electric  fuzes.  But  the  wires 
"X"  and  "Y"  need  not  be 
attached  to  adjoining  posts.  If, 
for  instance,  they  are  attached  to  posts  1  and  4,  the  test  repre- 

56 


sents  the  sum  of  the  intervening  numbers,  five,  ten  and  twenty, 
or  a  total  of  thirty-five  electric  fuzes. 

As  shown  by  the  numbers  stamped  upon  the  hard  rubber 
between  the  binding  posts,  a  large  number  of  tests,  representing 
from  five  up  to  one  hundred  electric  fuzes,  can  be  easily  made. 

In  testing  a  two  post  Blasting  Machine  (Fig.  2,  page  56), 
if  the  wires  "X"  and  "Y"  are  connected  with  the  binding  posts 
2  and  4,  the  effect  is  to  introduce  all  of  the  intervening  resistance 


..J 


Fig.  3 


into  the  circuit;  and  if  a  blasting  machine  so  connected  is  able 
to  fire  the  one  electric  fuze  used  as  an  indicator,  it  shows  that  it 
is  capable  of  firing  thirty  electric  fuzes  in  circuit. 

A  three  post  Blasting  Machine  (Fig.  4)  is  tested  in  practi- 
cally the  same  way,  except  that  there  are  two  circuits  to  test; 
that  between  binding  posts  "N"  and  "O,"  shown  by  plain  lines, 
and  that  between  "M"  and  "O,'* 
shown  by  dotted  lines.  It  will  be 
seen  at  a  glance  that  each  of  these 
circuits  is  identical  with  that  shown 
in  Fig.  2,  page  56.  If  the  blasting 
machine  is  a  Reliable  or  U.  S. 
Standard  No.  3,  the  rated  capacity 
of  which  is  thirty  electric  fuzes 
between  "N"  and  "O,"  or  thirty 
electric  fuzes  between  "M"  and 
"O,"  it  would  appear  that  its 
capacity,  when  using  three  leading 
wires,  should  be  the  sum  of  these  Fig.  4 

two  tests,  or  sixty  electric  fuzes ;    but  this  is  not  the  case,  for 

57 


when  both  circuits  are  used  at  one  operation  of  the  blasting 
machine,  the  capacity  of  each  circuit  is  reduced  to  about  twenty- 
two  electric  fuzes,  making  the  total  capacity  of  the  blasting 
machine  about  fifty  per  cent,  greater  when  three  leading  wires 
are  used  than  it  is  when  but  two  leading  wires  are  used.  This 
same  principle  applies  to  our  other  three  post  blasting  machines. 

If  two  Rheostats  are  available,  both  sides  of  the  blasting 
machine  can  be  tested  at  once  if  desired,  using  one  Rheostat  and 
one  electric  fuze  connected  as  shown  by  the  solid  lines  (Fig.  4, 
page  57),  and  the  other  Rheostat  and  another  electric  fuze  con- 
nected up  like  the  dotted  lines.  As  in  the  previous  tests,  the 
capacity  of  the  blasting  machine  is  indicated  by  the  sum  of  the 
numbers  between  the  two  binding  posts  on  the  Rheostat,  to  which 
the  wires  "X"  and  "Y"  are  attached. 

The  resistances  in  the  Rheostat  are  based  upon  30  foot 
electric  fuzes  and  the  required  surplus  resistance;  so  that,  if  the 
electric  fuzes  in  use  are  of  shorter  lengths,  it  will  be  possible  to 
fire  a  greater  number  than  this  test  will  indicate;  even,  in  some 
cases,  up  to  twice  the  number.  On  the  other  hand,  there  may 
be  circumstances  which  will  cut  down  the  number  that  can  be 
fired  below  what  the  Rheostat  test  will  indicate.  Chief  among 
these  will  be  leakage  of  electric  current  in  some  part  of  the  blasting 
circuit,  either  from  bare  joints  or  wire  touching  damp  ground,  or 
other  conductors,  or  from  fluids  of  great  penetrating  qualities 
coming  in  contact  with  the  insulation  of  the  wires  for  too  long 
a  time  before  firing.  Of  these  fluids,  the  worst  are  the  strong 
saline  liquids,  even  though  they  be  in  small  amounts,  found  in  salt 
mines,  and  the  bore  hole  washings  in  certain  kinds  of  rock.  If 
the  electric  fuzes  differ  greatly  in  sensitiveness  to  the  firing  current, 
this  will  also  cut  down  the  number  that  can  be  depended  upon 
to  fire  simultaneously. 

In  using  a  Rheostat,  do  not  connect  more  than  one 
electric  fuze  in  the  same  circuit  as  an  indicator,  because 
the  resistance  of  the  Rheostat  may  so  cut  down  the  electric 
current  from  the  blasting  machine  that  only  a  very  little  would 
be  left  to  pass  through  the  electric  fuzes.  If,  then,  two  or  more 

58 


electric  fuzes  be  used,  the  resistance  of  one  of  them  might  be 
sufficient  to  reduce  the  electric  current  to  such  an  extent  that  it 
would  not  heat  up  the  bridge  wire  in  the  others  quickly  enough 
to  explode  them  at  the  same  instant  that  the  first  one  exploded 
and  broke  the  circuit.  This  being  the  case,  it  can  be  clearly  seen 
that  the  Rheostat  is  not  a  true  indicator  of  the  capacity  of  the 
blasting  machine  when  more  than  one  electric  fuze  is  used  at  one 
time  with  it. 

Do  not  rely  on  one  test,  but  repeat  it  a  few  times,  so  as  to 
guard  against  accidentally  using  a  bad  electric  fuze  for  the  test. 
Again,  in  case  a  weak  blasting  machine  is  indicated  in  testing 
with  the  Rheostat,  make  sure  that  the  Rheostat  is  in  good  condi- 
tion, and  if  in  doubt,  try  the  blasting  machine,  before  finally 
condemning  it,  on  a  circuit  of  electric  fuzes  equal  to  the  rating  of 
the  blasting  machine. 


59 


Blasting  Caps 


Blasting  Caps 

LASTING  CAPS  are  made  in  four  different 
grades,  according  to  the  quantity  of  explosive 
material  with  which  they  are  charged.  This  ex- 
plosive material  is  very  sensitive  to  shock,  high 
temperature  or  a  spark,  which  necessitates  careful 
handling  if  accidents  are  to  be  avoided. 


Du  Pont  No.  5      Du  Pont  No.  6    Du  Pont  No.  7     Du  Pont  No.  8 
Gold  Medal  No.  5 

Blasting  Caps  (Actual  Size) 

The  following  table  describes  the  Blasting  Caps  illustrated 
above : 

Grade    ...    .    .    .  Gold  Medal 

Color  of  Box  .  . 
Length  of  Shell  . 
Caliber  of  Shell  . 
Distance  between  "j 

Top  of  Charge  > 

and  Top  of  Shell  J 
Weight  of     f  Grains 

Charge     \  Grams 


No.  5 

No.  5 

No.  6 

No.  7 

No.  8 

Black 

Blue 

Red 

Brown 

Green 

IX" 

IX" 

w 

!#' 

w 

.234" 

.234" 

.234" 

.234" 

.234" 

.78" 

.78" 

.765" 

.765" 

.718" 

12.34 

12.34 

15.43 

23.15 

30.86 

.80 

.80 

1.00 

1.50 

2.00 

63 


They  are  packed  in  tin  boxes,  holding  1 00  blasting  caps 
each.  These  are  put  up  for  shipment  in  strong  wooden  cases  of 
the  following  capacity : 

Case  No.  0 500  Blasting  Caps 

"       "1 1,000        " 

"      "2 2,000      " 

"      "3 3,000      " 

"      "5 5,000      " 

It  will  be  noted  that  the  number  of  the  case,  with  the 
exception  of  Case  No.  0,  corresponds  with  the  first  figure  of  the 
number  of  caps  packed  in  each  case.  As  no  case  containing 
4,000  is  packed,  there  is  no  Case  No.  4. 

Blasting  Caps  should  be  stored  in  a  dry  place,  and  when 
conveying  them  to  the  work  where  they  are  to  be  used,  no  moisture 
whatever  should  be  permitted  to  get  into  the  charge  which  they 
contain.  This  charge  is  very  easily  affected  by  dampness,  and 
will  absorb  moisture  and  deteriorate,  unless  the  blasting  caps  are 
kept  perfectly  dry.  Storage  in  damp  places,  such  as  tool  boxes 
in  mines,  is  likely  to  affect  the  charge  in  blasting  caps,  and,  while 
a  small  quantity  of  moisture  may  not  entirely  prevent  their  explod- 
ing, it  may  weaken  them  to  such  an  extent  that  they  will  not 
properly  detonate  high  explosives. 

Blasting  Caps  are  detonated  by  means  of  safety  fuse,  and 
the  methods  of  attaching  the  blasting  cap  to  the  fuse,  and  of  prim- 
ing high  explosive  cartridges  with  the  blasting  cap  and  fuse,  are 
covered  in  that  portion  of  this  catalogue  which  treats  of  safety  fuse. 


J 


Safety  Fuse 


TAK  ING  OUT  CAP 


CUTTING   FUSE 


PLACING  CAP  ON  FUSE 


CRIMPING 


* 


MAKING  HOLE  IN  TOP 
OF  CARTRIDGE 


FOLDING  CARTRIDGE 
PAPER  AROUND  FUSE 


INSERTING 
FUSE  AND  CAP  IN 
CARTRIDGE 


TYING  CARTRIDGE 
PAPER  AROUND  FUSE 


Priming  a  Dynamite  Cartridge  in  the  End 


Safety  Fuse 

AFETY  FUSE  may  be  used  with  blasting  caps 
to  detonate  high  explosives  when  it  is  not  neces- 
sary to  fire  more  than  one  charge  at  a  time.  It  may 
also  be  used,  without  blasting  caps,  to  explode 
blasting  powder.  Some  grades  can  be  used  in 
comparatively  wet  work  (provided  care  is  taken 
not  to  injure  the  fuse  when  tamping  the  bore  hole 
and  provided  the  charge  is  fired  promptly)  if  the 
joint  between  the  safety  fuse  and  blasting  cap  is  made  absolutely 
water  proof  with  soap,  tallow  or  similar  substance.  Oil  or  liquid 
grease  should  never  be  used,  because  they  are  likely  to  soak 
into  the  fuse  and  injure  the  powder  train.  Insulating  tape  can 
also  be  used  to  advantage  for  this  purpose. 

The  different  kinds  of  safety  fuse  may  be  divided  into  four 
general  classifications,  according  to  the  nature  of  the  work  for 
which  they  are  designed.  These  are : 

Dry  Work  Wet  Work 

Damp  Work  Under  Water 

It  must  be  remembered,  however,  that  good  results  will  not 
be  had,  even  under  this  classification,  unless  the  precautions 
in  regard  to  loading,  tamping,  etc.,  outlined  above  are  carefully 
observed.  For  example,  several  different  kinds  of  safety  fuse 
will  burn  through  satisfactorily  under  water  if  they  have  only  been 
under  the  water  for  a  short  time  and  at  no  appreciable  pressure, 
but  none  of  them  will  resist  water  under  pressure  for  many  hours. 

Most  fuse,  when  burning,  spits  fire  from  the  sides  and  gives 
off  a  relatively  large  volume  of  smoke.  This  is  highly  objection- 
able in  mines  where  the  ventilation  is  not  good  and  special  brands 
in  which  these  faults  are  reduced  as  much  as  possible  are  manu- 
factured for  this  work.  It  is  usually  necessary,  however,  when 

67 


reducing  smoke  and  "  side  spitting,"  to  sacrifice  somewhat  other 
desirable  qualities,  such  as  water  resistance,  regularity  of  burning, 
etc.  These  brands  are  listed  in  the  following  table  as  "Special." 


Safety  Fuse  Classification 


Dry  Work 

Hemp- White* 
Hemp— Black  t 
Cotton  * 
Superior  Mining  * 


Under  Water 
Triple  Tape— White* 
Triple  Taped— Black  t 
Stag* 

American  Eagle  t 
Pacific  f 
Acmef 
Eclipse  f 


Damp  Work 

Single  Tape— White  * 
Single  Taped— Black  f 
Beaver  * 
Blue  Label  f 
Sylvanite  f 

Special 

Special  XX* 
Special  XXX* 
Panther  f 
Shield  f 


Wet  Work 

Double  Tape-White* 

Double  Taped— Black  t 

Reliable* 

Victor  f 

Anchor  * 

Crescent  * 

Bearf 

Western  D.  T.  f 

Comet  t 


Hemp  Fuse  and  Cotton  Fuse  are  too  small  in  diameter  to 
properly  fit  the  standard  blasting  cap,  and  should  be  used  only  for 
exploding  blasting  powder  charges  where,  unless  a  dynamite 
primer  is  used,  a  blasting  cap  is  unnecessary. 

Safety  fuse  cannot  be  kept  in  good  condition  unless  stored 
in  a  coo/,  dry  place.  If  stored  in  a  hot  place,  the  heat  is  likely 
to  melt  the  varnish,  making  the  fuse  soft  and  black;  or  it  may  dry 
it  out  so  that  it  will  break  when  unrolled.  If  stored  in  a  damp 
place,  the  powder  in  the  fuse  soon  absorbs  moisture  and  fails  to 
burn  properly. 

When  handling  safety  fuse,  do  not  twist  or  "break"  it. 

Always  insert  the  fresh  cut  end  of  the  fuse  in  the  blasting 
cap,  because  the  powder  in  the  end  of  the  fuse  becomes  damp 
and  ineffective  very  quickly.  It  is  also  likely  to  spill  out  of  the 
cut  end  after  the  fuse  has  been  handled  a  little. 


*  Sold  east  of  Montana,  Wyoming,  Colorado  and  New  Mexico. 

t  Sold  west  of  and  including  Montana,  Wyoming,  Colorado  and  New  Mexico. 


68 


:EMP    (BLACK) 


Safety  Fuse 


Always  cut  the  end  of  the  safety  fuse  which  is  to  be  inserted 
in  the  blasting  cap  squarely  across  and  not  diagonally,  as  the  point 
made  by  a  diagonal  cut  may  be  bent  forward  when  the  safety 
fuse  is  pushed  into  the  blasting  cap,  and  in  this  way  prevent  the 
spark  from  shooting  into  the  blasting  cap  charge.  Always  press  the 
end  of  the  safety  fuse  gently  against  the  charge  in  the  blasting  cap 
before  crimping  the  blasting  cap.  All  safety  fuse,  except  Cotton 
and  Hemp,  is  made  to  fit  as  snugly  as  possible  into  the  blasting 
cap  in  order  to  prevent  water  or  moisture  from  entering.  If  the 
safety  fuse  is  found  at  any  time  to  be  a  little  too  large  to  enter  the 
blasting  cap,  do  not  attempt  to  cut  off  any  of  the  tape  or  yarn, 
but  swage  or  squeeze  the  end  until  it  is  small  enough. 

To  prime  a  dynamite,  or  other  high  explosive  cartridge, 
with  a  blasting  cap  and  safety  fuse,  make  a  hole  in  the  end  of  the 
cartridge  after  unfolding  the  paper  shell,  or  in  the  side  of  the  cart- 
ridge near  the  end,  with  a  pointed  stick  about  the  size  of  a  lead 
pencil.  This  hole  should  not  be  much  larger  in  diameter  than 
the  blasting  cap,  for  an  air  space  around  it  always  detracts  from 
the  force  with  which  a  bursting  blasting  cap  strikes  the  explosive 
surrounding  it.  Do  not  bury  the  blasting  cap  so  deep  in  the 
cartridge  that  the  safety  fuse  will  come  in  contact  with  the  explo- 
sive for  any  appreciable  distance,  as  the  "side  spitting"  of  safety 
fuse  usually  ignites  the  explosive. 

Best  results  will  be  had  if  the  blasting  cap  is  pointed  straight 
down  into  the  primer  cartridge. 

When  the  blasting  cap  has  been  put  in  the  end  of  the 
cartridge,  the  paper  must  be  folded  carefully  about  the  safety 
fuse  and  tied  securely  with  a  piece  of  string. 

When  the  blasting  cap  is  inserted  in  the  side  of  the  cartridge 
near  the  end,  the  safety  fuse  is  held  in  position  by  tying  it  to  the 
cartridge  with  a  double  loop  of  string.  Both  of  these  methods  of 
priming  are  clearly  illustrated  on  pages  66  and  7 1 .  Never  under 
any  circumstances  "lace"  fuse  through  the  primer  cartridge,  as  this 
will  almost  invariably  ignite  the  explosive  before  it  is  detonated, 
and  burning  dynamite  gives  off  exceedingly  poisonous  fumes. 

Each  package  of  safety  fuse  contains  two  50  foot  rolls, 
one  inside  of  the  other. 

69 


SAFETY  FUSE— Ensign-Bickford  and  Climax 

Brands 

(Sold  East  of  Montana,  Wyoming,  Colorado  and  New  Mexico) 

Approximate    Weights    and   Dimensions    of    Packages 
for  Domestic  Shipments 

COTTON  AND   HEMP 


Pkg. 

No. 

Packages 

Gross 
Weight 

Tare 

Net  Weight 

Outside  Dimensions 
of  Packages 

0 
1 
2 
3 
4 

500'  c/s  wood 
1,000'    "      " 
2,000'    "      " 
3,000'    "      " 
4,000'    "      " 

8     Ibs. 

26  2  " 
36^" 
55      " 

3     Ibs. 
6  2  " 
15  2  " 

5  Ibs. 

10     ' 
20     ' 
30    ' 

40    ' 

7tf  '    x    7^"  x  14|<" 
6#'   xllX"x!3" 
7#'   x  13"      x21^" 

14>I'   X15"      X20^' 

5 
6 
8 
10 
12 
12 

5,000'    "      " 

6,000'    "      " 
8,000'    "      " 
10,000'    "      " 
12,000'    "      " 
12,000'  bbl.   " 

68 
79       ' 
102       • 
124       ' 
146       ' 
145 

18 
19      " 
22      " 
24      " 
26      " 
25      " 

50    ' 

60    ' 
80  " 
100  " 
120  " 
120  " 

17"2     x20"2     x28>^' 
17"      x  20"      x  32^' 
23"      x  30" 

SPECIAL    XX,    SPECIAL    XXX,    BEAVER,    ANCHOR, 
CRESCENT,   STAG 


Pkg. 

No. 

Packages 

Gross 
Weight 

Tare 

Net  Weight 

Outside  Dimensions 
of  Packages 

0 

500'  c/s  wood 

lO^lbs. 

3    Ibs. 

7^1bs 

7"      x    7^'   x!5" 

1 

1,000'    "      " 

19  /2    " 

4/4  " 

15  2    '* 

7%'   x  13^'   x  14^" 

2 

2,000'    "      " 

36^" 

6/4  " 

30       ' 

13>£'   x  13#'   x  15" 

3 

3,000'    "       ' 

60      " 

15      " 

45       * 

14^'   x  13^'   x20>^" 

4 

4,000'    "       ' 

78      " 

18      " 

60       « 

14y2'   x20^'   x  20^" 

5 

5,000'    " 

94      " 

19      " 

75       ' 

14^'   x20^'   X24" 

6 

6,000'    "       ' 

112      " 

22      " 

90       ' 

14^'   x  20^'   x  27V" 

8 

8,000'  bbl.    ' 

145      " 

25      " 

120       ' 

23"      x  30" 

SINGLE,    AND    DOUBLE    TAPE,    SUPERIOR    MINING, 
RELIABLE 


Pkg. 

No. 

Packages 

Gross 
Weight 

Tare 

Net  Weight 

Outside  Dimensions 
of  Packages 

0 

500'  c/s  wood 

11     Ibs. 

3     Ibs. 

8  Ibs. 

7"      x    7#'  x!5" 

1 

1,000'    "       " 

20^" 

4^" 

16   " 

7^"xl3K'   x!4^" 

2 

2,000'    "       " 

36^" 

6^" 

32   " 

13^"xl3^'   x!5" 

3 

3,000'    "      " 

63     " 

15      " 

48  " 

14^"X15"      x20K" 

4 

4,000'    "      " 

82      " 

18      " 

64  " 

14K"x20^'   x20^" 

5 

5,000'    "      " 

99      " 

19      " 

80  " 

14^"x20^'   x24" 

6 

6,000'    ••      " 

118      " 

22      " 

96  " 

IW  x20><'   x27|/" 

8 

8,000'  bbl.    " 

153      " 

25      " 

128  " 

23"      x  30" 

70 


CUTTING  FUSE 


TAKING  OUT  CAP 


PLACING  CAP  ON   FUSE 


MAKING   HOLE   IN 
SIDE  OF  CARTRIDGE 


INSERTING 

FUSE  AND  CAP  IN  SIDE 
OF  CARTRIDGE 


TYING    STRING    TO    F 


TYING  FUSE 
TO  C  A  R-TP  I  DGE 


Priming  a  Dynamite  Cartridge  in  the  Side 


FUSE — Ensign-Bickford  Brands — Continued 
TRIPLE  TAPE 


Pkg. 

No. 

Packages 

Gross 
Weight 

Tare 

Net  Weight 

Outside  Dimensions 
of  Packages 

0 

500'  c/s  wood 

12     IBs. 

3     IBs. 

91bs. 

7"      x    7X"xl5" 

1 

1,000' 

22^   * 

4^" 

18  " 

7#"xl3^"xl4^" 

2 

2,000' 

42^   • 

6^" 

36  " 

13^"xl3^"xlo" 

3 

3,000' 

69       • 

15      " 

54  ' 

14X"xl5"      x20^" 

4 

4,000' 

90       ' 

18      " 

72  ' 

14^"x20X"x20^" 

5 

5,000' 

109       ' 

19      " 

90  ' 

14%"  x  20^"  x  24" 

6 

6,000' 

130      • 

22      " 

108  • 

14K"'x20^"x27^" 

7 

7,000'  bbl. 

151      " 

25      " 

126   ' 

23"      x  30" 

SAFETY  FUSE 

(Sold  West  of  and  Including  Montana,  Wyoming,  Colorado  and 
New  Mexico) 

Approximate  Weights  and  Dimensions  of  Packages 
for  Domestic  Shipments 


SINGLE  TAPE—  WHITE                         ACME 

DOUBLE  TAPE—  WHITE                       SHIELD 

TRIPLE  TAPE—  WHITE                         SYLVANITE 

WESTERN  D.  T. 

Pkg. 
No. 

Packages 

Gross 
Weight 

Tare 

Net  Weight 

Outside  Dimensions 
of  Packages 

1 

2 

3 
4 
5 
6 

1,000 
2,000 
3,000 
4,000 
5000 
6,000 

19j£  Ibs. 
38       " 

58       " 

89^    •• 
105^   " 

4^  Ibs. 

"isj?  •• 

13       " 
15 

17       " 

14  #  Ibs. 

29^    " 

44^    " 
59^    " 

74^    " 
88^    " 

8"/,,  *  12',', 
15^'".xl5V 

,  *  24lf 
^  x  SO"' 

SINGLE  TAPED— Black 


Pkg. 

No. 

Packages 

Gross 
Weight 

Tare 

Net  Weight 

Outside  Dimensions 
of  Packages 

1 
3 
6 

1,000 
3,000 
6,000 

23      Ibs. 
59 
110 

8      Ibs. 
15       " 
23       " 

15      Ibs. 
44 
87       " 

7^"  x  14#"  x  13" 
8X"xl5^"x37" 
14^"  x  15#"  x  37" 

72 


Safety  Fuse, 


FUSE— Continued 
DOUBLE  TAPED— Black 


Pkg. 

No. 

Packages 

Gross 
Weight 

Tare 

Net  Weight 

Outside  Dimensions 
of  Packages 

1 

1000 

24      Ibs. 

8      Ibs. 

16      Ibs. 

8X"xl4^"xl3" 

3 

3,000 

62^    " 

15       " 

47^    " 

8l/2"  x!5^"x37" 

6 

6,000 

119       " 

23       " 

96 

14J£"  xlo^"  X37" 

TRIPLE   TAPED— Black 


Pkg. 

No. 

Packages 

Gross 
Weight 

Tare 

Net  Weight 

Outside  Dimensions 
of  Packages 

1 

1,000 

24      Ibs. 

8      Ibs. 

16      Ibs. 

8^"xl4>£"  X13" 

3 

3,000 

66       " 

15 

51 

8^"xl5^"x37" 

6 

6,000 

125^    " 

23       " 

102^    " 

14^"  x  15^"  x  37" 

BLUE  LABEL,   VICTOR,    AMERICAN  EAGLE 


Pkg. 

No. 

Packages 

Gross 
Weight 

Tare 

Net  Weight 

Outside  Dimensions 
of  Packages 

1 

1,000 

23      Ibs. 

8      Ibs. 

15      Ibs. 

7^"xl4K"xl3" 

3 

3,000 

60        " 

15 

45 

Wxl5>£"x37" 

6 

6,000 

113        " 

23       " 

90       " 

14>£"xl5>£"x37" 

BEAR 


Pkg. 

No. 

Packages 

Gross 
Weight 

Tare 

Net  Weight 

Outside  Dimensions 
of  Packages 

1 

1,000 

23      Ibs. 

8       Ibs. 

15      Ibs. 

7^"xl4^"xl3" 

3 

3,000 

61 

15 

46        " 

8/2"  xl5/2"  x37" 

6 

6,000 

117^    " 

23        " 

94^    " 

14^"xl5X"x37" 

PACIFIC 


Pkg. 

No. 

Packages 

Gross 
Weight 

Tare 

Net  Weight 

Outside  Dimensions 
of  Packages 

1 

1,000 

23      Ibs. 

8      Ibs. 

15      Ibs. 

8^"xl4X"  x!3" 

3 

3,000 

60       " 

15       " 

45 

8^"  x  15y2"  x37" 

6 

6,000 

114       " 

23 

91 

14^"  x  15^"  x  37" 

HEMP 


Pkg. 

No. 

Packages 

Gross 
Weight 

Tare 

Net  Weight 

Outside  Dimensions 
of  Packages 

10 

10,000 

114      Ibs. 

23      Ibs. 

91      Ibs. 

14X"xl5^"x37" 

*  Packed  only  in  full  cases  10,000'  each. 

73 


FUSE— Continued 
COMET 


Pkg. 

No. 

Packages 

Gross 

Weight 

Tare 

Net  Weight 

Outside  Dimensions 
of  Packages 

3 
6 

3,000 
6,000 

64      Ibs. 

122 

14       Ibs. 
23       " 

50      Ibs. 

99 

8>£"xl5Vx37" 
U}/2"  *  15J/2"  -X.S7" 

ECLIPSE 


Pkg. 
No. 

Packages 

Gross 
Weight 

Tare 

Net  Weight 

Outside  Dimensions 
of  Packages 

3 
6 

3,000 
6,000 

60      Ibs. 
ll&/2    " 

14       Ibs. 
23 

46      Ibs. 

93^    " 

8X"xl5Vx37" 
14V'  *  io^"  *  37" 

74 


Safety  Fuse 


Cap  Crimpers 
Thawing  Kettles 
Tamping  Bags 
Blasting  Mats 


Cap  Crimpers 


N^    O  blasting  equipment,  where  safety  fuse  and  blast- 
I     ing  caps  are  used,  is   complete  without  a  Cap 
Crimper.     This  inexpensive  little  tool  will  wear 
I     for  years,  and  pay  for  itself  many  times  over  in  a 
day;  yet  many  blasters  fail  to  appreciate  its  value, 
and  resort  to  a  knife  or  their  teeth  to  fasten  the 
blasting  cap  to  the  safety  fuse.     Besides  being 
exceedingly  dangerous,  both  of  these  methods  are 
ineffective,  and  often  responsible  for  expensive  misfires. 

The  accompanying  illustrations  show  plainly  why  a  cap 
crimper,  and  not  the  teeth  or  a  knife,  should  be  used  to  attach 
the  blasting  cap  to  the  safety  fuse. 


BLASTING    CAP   FASTENED   ON    FUSE 
NO.    1 


BLASTING    CAP   FASTENED   ON    FUSE   WITH    A    KNIFE 

No.  2 


BLASTING    CAP   CRIMPED   ON    FUSE   WITH    A    DU  PONT   CAP   CRIMPER 

No.  3 

The  blasting  cap  should  be  very  securely  fastened  to  the 
safety  fuse,  both  to  prevent  the  fuse  from  being  pulled  out  of  it 
when  the  primer  cartridge  is  loaded  and  the  bore  hole  tamped, 


77 


and  also  to  keep  the  charge  in  the  blasting  cap  dry  if  water 
is  present.  This  can  only  be  accomplished  by  the  use  of  an 
instrument  made  especially  for  the  purpose. 

The  Du  Pont  Cap  Crimper  is  equipped  with  an  effective 
fuse  cutter  and  has  a  straight  arm  with  which  the  hole  for  the 
blasting  cap  can  be  made  in  the  primer  cartridge.  The  other 
arm  has  a  hole  in  it  for  a  string  or  chain,  so  that  it  can  be  attached  to 
the  blaster,  and  will  not  be  somewhere  else  when  it  is  most  wanted. 


Du  Pont  Cap  Crimper 

This  crimper  is  so  made  that  it  cannot  press  the  blasting 
cap  far  enough  into  the  fuse  to  cut  off  the  powder  train  and 
cause  a  misfire. 


Thawing  Kettles 

Many  high  explosives  containing  nitroglycerin  freeze  and 
become  insensitive  in  cold  weather,  and  when  frozen  may  burn 
instead  of  explode.  Burning  dynamite  gives  off  fumes  so  poisonous 
that  men  have  been  killed  by  it.  It  is  obvious,  therefore,  that 
when  dynamite  that  freezes  is  to  be  used  in  low  temperatures 
some  provision  must  be  made  for  thawing  it  and  for  peeping  it 
thawed  until  it  is  loaded  into  the  bore  hole.  As  this  dynamite, 
Red  Cross  excepted,  freezes  at  about  45°  F.  or  50°  F.,  the 
thawing  problem  is  a  troublesome  one.  On  work  where  these 
explosives  are  used  in  large  quantities,  thawing  houses*  are  neces- 
sary; but  even  then  the  Thawing  Kettle  should  be  employed  to 
take  the  explosives  from  the  thawing  house  to  the  place  where 
they  are  to  be  used,  in  order  to  prevent  them  from  becoming  chilled 
or  frozen  again.  If  not  more  than  two  or  three  hundred  pounds  of 
explosives  are  used  at  one  time,  three  or  four  large  thawing  kettles 

*See  our  Booklet  on  Thawing  Dynamite,  mailed  on  application. 

78 


are  all  that  are  necessary,  and  will  thoroughly  thaw  that  quantity 
of  frozen  dynamite  in  a  few  hours. 

These  thawing  kettles  are  all  made  with  a  water  tight 
compartment  for  the  explosives  (dynamite  should  never  under  any 
circumstances  be  permitted  to  come  in  contact  with  hot  water), 
which  is  surrounded  by  the  receptacle  for  the  hot  water.  The 
Catasauqua  Thawing  Kettles  are  in  one  piece,  but  the  Bradford 
Thawing  Kettles  consist  of  two  receptacles,  the  one  for  the 
explosive  fitting  into  the  one  for  the  hot  water. 

The  Miners'  Thawing  Kettle  has  the  hot  water  compart- 
ment surrounded  by  a  jacket  of  non-conducting  material.  The 
water  in  this  thawing  kettle  will  remain  warm  for  from  five  to 
eight  hours,  even  in  very  cold  weather.  It  will  thaw  from  21  to 
28  pounds  of  dynamite  without  having  the  water  compartment 
refilled. 

The  Catasauqua  and  the  Bradford  Thawing  Kettles  will 
retain  their  heat  about  five  times  as  long  if  they  are  kept  in  a 
barrel  with  dry  hay  surrounding  them  as  they  will  if  this  is  not 
done.  This  hay  can  be  held  in  place  by  a  cylinder  of  wire  screen, 
so  that  the  thawing  kettle  can  easily  be  removed  and  replaced. 
If  the  barrel  be  mounted  on  two  wheels  with  a  tongue  attachment, 
it  can  be  readily  drawn  from  point  to  point  about  the  work,  so 
that  it  will  not  be  necessary  to  expose  the  dynamite  to  the  cold 
air  until  it  is  to  be  loaded  in  the  bore  hole. 

Under  no  circumstances  must  the  water  be  heated  in  either 
the  Catasauqua  or  Miner's  Thawing  Kettles,  even  though  the 
explosives  be  first  removed,  because  nitroglycerin  exudes  very 
readily  from  warm  dynamite,  and  enough  of  it  is  likely  to  be 
found  in  the  bottom  of  the  explosives  compartment  of  a  thawing 
kettle  that  has  been  in  use  for  some  time,  to  cause  a  serious 
accident  were  the  thawing  kettle  placed  over  a  fire.  In  addition 
to  this,  the  insulating  jacket  of  the  Miner's  Thawing  Kettle  would 
be  destroyed  were  it  subjected  to  a  high  temperature.  The 
water  receptacle  of  the  Bradford  Thawing  Kettle  may  be  used 
for  heating  the  water  if  the  explosives  receptacle  be  removed,  but 
it  is  necessary  with  both  the  Catasauqua  and  Miner's  Thawing 

79 


Kettles  to  heat  the  water  in  something  else  before  filling  the  water 
jacket.  The  hot  water  must  always  be  tested  before 
filling  the  dynamite  compartment.  If  it  is  hot 
enough  to  burn  the  hand,  do  not  put  the  explosives 
into  the  Thawing  Kettle.  Never  fill  the  water  jacket 
unless  the  explosives  compartment  is  empty,  and  see  that  the 
explosives  compartment  is  perfectly  dry  before  it  is  filled. 


Bradford  Thawing  Kettle 


Miner's  Thawing  Kettle 


Catasauqua  Thawing  Kettle 


Capa- 
city 

Weight 
Empty 

Weight  of 
Water 

Total  Wt. 
Filled 

Outside  Dimensions 

Bradford  No.  1  .    .    . 

22  Ibs. 

14      Ibs. 

58^  Ibs. 

94^  Ibs. 

16"      x  21" 

Bradford  No.  2  .    .    . 

60   " 

20 

110 

190 

21"      x  21" 

Catasauqua  No.  1  .    - 
Catasauqua  No.  2  .    . 

30  " 
60   " 

17$    " 

40        " 

82^    " 
155 

14"      x!4^" 
17%"  x  21" 

Miner's  ...... 

7  " 

8/2    " 

7 

22^    " 

8/2"x9"xl2^" 

80 


1/2X1S 


Tamping  Bag 
(Full) 


Tamping  Bags 

Tamping  Bags  of  heavy  paper 
are  used  in  many  places  as  con- 
tainers for  tamping  and  save  time 
and  trouble  when  loading  bore 
holes,  particularly  the  pitching  ones 
and  the  "uppers." 

They  are  also  employed  as 
containers  for  blasting  powder  when 
the  miner  or  blaster  desires  to  make 
up  the  charge  in  cartridge  form,  as 
is  generally  the  custom  when  it  is 
used  in  mines  or  in  open  work  that 
is  damp. 

Tamping  Bags  are  put  up  in 
bundles  of  500  each  and  packed 
ten  bundles  to  the  bale.  They  are 
manufactured  in  the  following  sizes: 


TAMPtNS  BAGS 


Tamping  Bag 

(Empty] 


Size  No. 

Size 

No.  in  Bale 

Shipping  Weight 
per  Bale 

A 

1"      x    8' 

5,000 

28      Ibs. 

B 

IX' 

x    8' 

5,000 

31 

C 

IX' 

xlO' 

5,000 

37  X 

D 

IX' 

x!2' 

5,000 

45 

E 

IX' 

x    8' 

5,000 

36 

F 

IX' 

xlO' 

5,000 

44 

G 

W 

x!2' 

5,000 

48       " 

H 

IX' 

x!6' 

5,000 

62 

J 

2"      x  18' 

5,000 

86       " 

Tamping  Bags  are  made  approximately  2  inches  longer 
than  shown  in  the  above  table,  in  order  to  provide  for  folding  at 
the  end  when  in  use. 


81 


Blasting  Mats 

Blasting  Mats  are  made  of  woven  rope.  Hemp  is  generally 
used  and  is  considered  the  best,  although  steel  wire  rope  has  been 
tried.  The  mats  are  made  of  1  inch,  1  /^  inch  or  1  Y?,  inch  rope, 
according  to  the  demands  of  the  customer.  They  are  not  carried 
in  stock,  but  are  woven  on  order  and  are  made  in  any  size  required. 
If  the  blasting  mats  are  to  cover  light  charges  of  explosives,  they 
may  be  spread  on  the  rock  directly  over  the  bore  holes;  but  if 
heavier  charges  are  used,  railroad  ties  or  logs  should  be  put  down 
first  and  the  mats  on  top  of  them.  This  arrangement  is  very 
effective  in  preventing  the  rock  from  being  thrown  into  the  air  and 
should  always  be  adopted  when  blasting  is  done  near  thorough- 
fares or  buildings. 


82 


The  Advantage 

of 
Strong  Detonators 


The  Advantage  of  Strong  Detonators 

HEN  high  explosives  are  detonated,  the  stronger 
or  sharper  the  initial  shock  the  quicker  and  more 
thorough  is  the  detonation  of  the  charge.  It  is  a 
well  known  fact  that  certain  detonating  substances 
will  exert  this  effect  more  powerfully  than  others. 
To  obtain  the  full  value  of  the  explosive  charge,  it 
should  be  detonated  as  quickly  and  as  completely  as 
possible.  If  the  detonation  is  slow  and  incomplete, 
a  greater  quantity  of  explosive  is  required  to  do  the  same  work, 
and  large  volumes  of  poisonous  gases  are  evolved — a  matter  of 
serious  consequence  when  the  work  is  underground,  instances 
being  known  where  workmen  have  been  killed  by  gases  given 
off  from  partially  detonated  or  burning  explosives.  Quick  and 
complete  detonation  results  in  a  minimum  of  flame,  a  point  of 
first  importance  with  those  explosives  intended  for  use  in  the 
presence  of  inflammable  gas  or  coal  dust.  Electric  fuzes  or 
blasting  caps  too  weak  to  detonate  a  charge  of  high  explosives 
frequently  generate  sufficient  heat  to  ignite  it,  while  slightly  stronger 
ones  may  partially  detonate  it.  Still  stronger  ones  may  cause 
complete  detonation,  but  with  insufficient  rapidity  to  give  best 
results. 

The  effect  of  a  detonator  on  a  charge  of  high  explosives  in 
a  bore  hole  is  not  infinite,  but  decreases  with  distance.  It  is, 
therefore,  easy  to  understand  the  necessity  for  using  detonators 
sufficiently  strong  for  the  effect  of  the  detonator  itself  to  extend 
throughout  the  charge.  It  might  be  understood  from  this  that  the 
detonator  should  be  located  in  the  center  of  the  charge;  this 
would  be  correct  had  not  numerous  tests  shown  that  the  greatest 
effect  of  the  detonator  is  straight  away  from  its  loaded  end  and 
in  a  line  with  its  long  axis. 

85 


In  deep  bore  holes  loaded  with  long  charges,  whether  they 
be  fired  with  fuse  and  blasting  caps  or  with  electric  fuzes,  it  is 
well  to  place  a  blasting  cap  in  a  cartridge  of  the  explosive,  at 
intervals  of  about  5  feet  throughout  the  charge,  so  that  their  effect 
will  extend  the  entire  length  of  the  charge.  It  is  also  advisable 
to  use  two  electric  fuzes  in  deep  bore  holes,  so  that  if  one  should 
be  defective,  the  other  may  be  depended  on  for  the  initial 
detonation.  A  point  to  be  remembered  in  buying  detonators  is 
that  the  charge  which  they  contain  is  readily  affected  by  moisture, 
and  consequently,  unless  storage  conditions  are  of  the  best,  a  fair 
margin  of  safety  in  strength  should  be  allowed.  Blasting  caps, 
being  open  at  one  end,  are  more  quickly  weakened  by  dampness 
than  are  electric  fuzes. 

Another  strong  argument  for  allowing  a  fair  margin  of  safety 
when  buying  detonators  is  the  very  small  cost  of  the  detonator 
in  comparison  with  that  of  the  charge  of  explosives  with  which 
it  is  used.  It  is  difficult  to  understand  why  anyone,  in  order  to 
save  a  few  cents  on  the  price  of  a  hundred  detonators,  would  risk 
the  misfire,  partial  detonation  or  imperfect  work  of  the  charge  of 
explosives  in  a  bore  hole,  which  results  at  best  in  the  loss  of  several 
dollars  and  may  cost  thousands  if  it  burns  in  a  gaseous  coal  mine  or 
if  unexploded  dynamite  happens  to  cause  a  fatal  accident  afterward. 

The  following  from  one  of  our  customers  who  was  driving 
a  railroad  tunnel  shows  how  thoroughly  those  who  have  used 
strong  detonators  recognize  their  value.  The  5X  blasting  cap 
referred  to  is  now  known  as  the  Du  Pont  No.  5  and  the  No. 
30  Special  is  the  present  Du  Pont  No.  8. 

Montana,    1  1/30/07. 
E.  I.  du  Pont  de  Nemours  Powder  Co. 

Dear  Sir :  In  reply  to  your  request  for  information  as  to  the  efficiency 
of  your  No.  30  Special  Blasting  Caps,  I  submit  the  following  comparison : 

No.  5  X  Caps  No.  30  Special  Caps 

No.  of  holes,  average 34  per  shift  25 

No.  sticks  powder  per  hole 12  9 

Minutes  before  force  was  able  to  return  to  work,  15  5 

We  have  had  great  success  with  every  hole  since  using  your  No.  30 
Special,  and  the  shift  bosses,  etc.,  are  very  enthusiastic  about  them. 

86 


The  rock  to  be  blasted  was  very  hard  granite  in  a  tunnel.  Great  diffi- 
culty was  experienced  in  breaking  the  rock,  especially  in  the  heading. 

This  was  drilled  about  6  feet,  but  all  holes  were  shot  twice.  The 
section  was  only  8  feet  x  1  6  feet,  but  a  large  number  of  holes  was  necessary 
on  account  of  the  hard  and  tough  rock. 

By  the  use  of  the  No.  30  Special,  we  saved  outright  the  work  of  one 
machine  for  one  shift,  and  in  that  same  shift  20  pounds  of  powder  and  at 
least  20  minutes  time  for  the  entire  force  of  about  20  men. 

This  is  quite  a  saving  and  demonstrates  beyond  a  doubt  that  the  No. 
30  Special  is  the  best  cap  for  hard  rock. 

The  above  report  shows  the  results  of  a  test  on  which  close  account 
was  kept  for  a  period  of  1 0  days. 

Yours  very  truly,  etc. 

The  extended  study  and  tests  of  explosives,  conducted  dur- 
ing the  past  few  years  by  the  United  States  Bureau  of  Mines, 
have  clearly  demonstrated  the  economy  of  using  only  strong 
detonators.  On  page  52  of  Bulletin  423,  "A  Primer  on 
Explosives  for  Coal  Miners,"  issued  by  the  Department  of  the 
Interior,  occurs  the  following: 

"In  the  appendix  setting  forth  the  test  requirements  for  permis- 
sible explosives,  it  is  stated  that  electric  or  other  detonators, 
containing  not  less  than  1  gram  of  the  fulminating  composition, 
should  be  used  in  firing  the  charges.  For  use  with  high  explosives 
in  rock  blasting,  detonators  of  that  strength  are  also  best.  Under 
no  circumstances  should  an  electric  or  other  detonator  be  used 
of  less  strength  than  No.  5,  containing  0.8  gram  of  the  fulminating 
composition.  The  greater  efficiency  and  certainty  of  the  stronger 
detonator  more  than  make  up  for  the  slightly  greater  cost." 

The  clause  in  the  Appendix  of  Bulletin  423,  referred  to 
above,  states:  "That  No.  6  detonators,  preferably  No.  6  electric 
detonators  (double  strength),  are  used  of  not  less  strength  than 
1  gram  charge,  consisting  by  weight  of  90  parts  of  mercury 
fulminate  and  1 0  parts  of  potassium  chlorate  (or  its  equivalent)," 
etc.  The  Du  Pont  No.  6  Blasting  Cap  and  Victor  No.  6  Electric 
Fuze,  recommended  throughout  this  catalogue  for  detonating  high 
explosives,  comply  with  the  above  specifications. 

87 


Strong  electric  fuzes  and  blasting  caps  should  be  used  with 
all  high  explosives: 

Because  they  insure  complete  detonation. 

Because    they    increase    the    execution    of    the 
explosive. 

Because  they  tend  to  counterbalance  careless  and 
improper  usage. 

Because  they  offset,  to  some  extent,  deterioration 
due  to  improper  storage. 

Because  they  reduce  fumes  from  the  explosive 
to  a  minimum. 

Because  they  decrease  the  size  and  duration  of 
flame. 

Because  they  prevent  the  loss  of  the  charge  by 
burning. 

Because  their  effect  carries  farther  in  long  charges. 
Because  they  reduce  the  chances  of  misfire. 


The  Elementary 
Principles   of   Electricity 


AS   APPLIED   TO   ELECTRIC    BLASTING 
and 

Some  Useful   Information   as   to  Methods  of  Using,  Preserving  and 
Testing  the   Blasting   Equipment 


From  "PRINCIPLES  OF  ELECTRIC  BLASTING, "  by  W.  G.  Hudson,  M.  D. 


No.  6  No.  7  No.  8 


No.  5  No.  6  No.  7  No.  8 

Du  Pont  Blasting  Caps  and  Victor  Electric  Fuzes  (actual  size) 


CHAPTER    1 

Elementary  Electrical  Principles 

1 .  In  Fig.  1  is  shown  an  ordinary  dry  cell  battery,  with  its 
two  binding   posts    or   connectors  (A-B).     These  are    called, 
respectively,  the  Positive  and  Negative  Poles. 

If  the  poles  are  connected  with  a  piece  of  wire  (C)  an 
electric  current  will  flow  through  it,  in  the  direction  indicated  by  the 
arrows,  and  will  continue  to  flow  until  the  chemicals 
are  exhausted. 

2.  Such  a  wire  affording  a  path  for  the  cur-| 
rent  from  the  positive  to  the  negative  pole  of  a  bat- 
tery is  called  a  circuit.    The  current  only  flows  when 
the  circuit  is  complete,  and  a  single  break  in  the 
continuity    of  the   wire    stops  the  flow  of  current 
throughout  the  entire  circuit. 

The  wire  comprising  the  circuit  can  be  much 
longer  than  shown  in  Fig.  1  — even  many  miles  in 
length — and  still  the  current  will  follow  it  through- 
out its  entire  length,  so  long  as  some  shorter  or 
easier  path  between  the  two  poles  is  not  offered. 
If  the  wire  is  covered  with  some  insulating  material 
like  silk,  rubber  or  cotton,  so  as  to  prevent  the  current  from  escap- 
ing from  it  and  following  some  shorter  or  easier  course,  then  the 
wire  may  be  wound  many  times  around  other  objects,  or  make 
any  number  of  bends  and  twists,  and  still  the  current  will  follow 
it  from  one  pole  of  the  battery  to  the  other,  with  almost  as  much 
ease  as  it  did  the  short  piece  of  wire  in  Fig.  1 . 

3.  Now,  how  do  we  know  that  a  current  is  flowing  through 
the  wire  in  the  manner  described?     We  know  it  by  its  effects, 
and  a  few  of  these  effects,  which  are  of  great  importance  in 

91 


understanding  blasting  by  electricity,  will  answer  for  the  present 

consideration. 

3 -A.  First,  if  part  of  the  ordinary  thick 
copper  wire  used  in  Fig.  1  be  replaced  by  a  very 
fine  piece  of  wire  ("G,"  Fig.  2),  the  fine  wire 
being  preferably  of  iron,  platinum  or  German 
silver,  then  the  difficulty  which  the  current  has 
in  passing  through  this  small  piece  of  wire,  or,  as 
electricians  say,  "overcoming  its  resistance,"  will 
transform  part  of  the  current  into  heat.  The  fine 
wire  will  become  red  hot,  and  even  melt  if  the 
current  is  strong.  This  is  the  principle  made  use 
of  in  firing  electric  fuzes.  Another  familiar  ap- 
plication is  the  incandescent  electric  light,  where 
a  fine  carbon  wire  is  forced  to  carry  a  large 
amount  of  current,  and  becomes  so  intensely 

white  hot  (incandescent)  that  it  gives  out  light. 

3-B.  Second,  if  wire  insulated  with  cotton  or  silk*  be  wound 
many  times  around  a  bar  of  ordinary  soft  iron  (Fig.  3,  page  93), 
the  ends  of  the  wire  being  connected  with  a  battery  so  that  the 
current  will  flow  through  it,  the  iron  bar  will  be  found  to  become 
powerfully  magnetic.  As  soon  as  the  circuit  is  interrupted"}*  at 
any  point,  whether  by  removing  one  or  both  wires  from  the  battery, 
or  breaking  or  cutting  the  wire  anywhere  throughout  its  length, 
nearly  all  the  magnetism  J  immediately  departs  from  the  iron. 

*  Non-conductors  are  those  substances  which  do  not  carry  the  electric  current. 
Conductors  are  those  substances  which  carry  it  readily;  poor  conductors  are  those  which 
carry  it,  but  with  difficulty.  Strictly  speaking,  there  are  no  perfect  non-conductors,  and  no 
perfect  conductors;  but  the  terms  are  in  common  use  and  are  convenient  and  unobjectionable 
if  it  is  borne  in  mind  that  they  are  relative.  Metals  are  the  best  conductors ;  silver  heads 
the  list,  followed  in  turn  by  copper,  zinc,  iron,  platinum,  lead,  mercury,  etc.  Among  the 
best  non-conductors  are  glass,  rubber,  sulphur,  silk,  cotton,  paraffin,  tar,  resinous  materials, 
oils,  etc.  Water  is  a  representative  of  poor  conductors,  but  its  conductivity  is  greatly  in- 
creased when  various  salts,  such  as  those  likely  to  be  derived  from  rocks  in  drilling,  are 
dissolved  in  it.  Acids  also  increase  the  conductivity  of  water. 

t  Interrupting  or  breaking  a  circuit  at  any  point  is  referred  to  by  electricians  as  "open- 
ing" the  circuit;  re-establishing  it,  so  that  the  current  can  pass,  as  "closing"  the  circuit. 

J  Soft  iron  readily  loses  nearly  all  its  magnetism  as  soon  as  the  current  stops,  and  the 
softer  the  iron  the  more  readily  it  becomes  demagnetized,  although  it  never  loses  all  of  it. 
Hard  steel,  on  the  contrary,  retains  a  great  deal  of  magnetism  once  it  has  been  magnetized, 
and  on  this  principle  depends  a  permanent  magnet.  The  magnetism  left  in  an  electromagnet 
after  the  current  has  ceased  is  called  "residual  magnetism." 

92 


Fig.  3 


As  soon  as    the    circuit   is    closed,  the 
magnetism    returns,     even    though    the 
opening  and  closing  of  the  circuit  is  per- 
formed  many   times  a  second,  and  the 
point  of  interruption  is  in  a  far  distant 
part  of  the  circuit.     If  another  piece  of  iron  for 
the  magnet  to  attract  is  balanced  by  a  spring  over 
the  magnet,  every  time  the  circuit  is  closed  it  will 
be  drawn  toward  the  magnet,  and  when  the  cir- 
cuit is    opened   the  spring  will   draw  it    away. 
Such  a  piece  of  iron  provided  for  the  magnet  to 
act  upon  is  called  an  armature.     The  telegraph 
sounder  (Fig.  3^4)  works    on    this    principle, 
the    armature  in    its  up  and  down    movements 
causing  a  lever  to  strike  resonant  metal  pegs,  which  give  out  the 

familiar  "clicks,"  by  the  sound 
of  which  the  operator  reads 
the  message.  Many  other 
electrical  instruments  also  work 
on  this  same  principle. 

C.  Third,  that  an  elec- 
tric current  is  flowing  through  the  wire  (Fig.  1  ,  page  9  1  )  can  be 
shown  by  crossing  part  of  the  wire  over  a  compass  as  shown  in 
Fig.  4.  Ordinarily,  of  course,  the  needle  of  the  compass  will 
point  north  and  south,  and  the  wire 
above  it  should  run  in  the  same 
direction.  But  as  soon  as 
the  connection  with  the  bat- 
tery is  established  the  needle 
will  be  deflected,  so  that  it 
will  stand  at  right  angles  to 
the  wire,  or,  in  other  words, 

point  east  and  west.  If  the  end  of  the  wire  that  is 
connected  with  the  positive  pole  of  the  battery  be 
transferred  to  the  negative  pole,  and  vice  versa 
(that  is,  if  the  "poles  be  changed")  the  needle  will 

93 


pig. 


reverse  its  direction,  so  that  the  end  which  pointed  east  before 
will  now  point  west. 

4.  The  needle  will  also  reverse  its  direction  if  the  wire  "C," 
Fig.  4,  be  moved  from  its  position  above  the  needle  to  one  below 
it,  as  shown  by  the  dotted  line.     In  other  words,  the  direction  of 
the  electric  current  affects  the  direction  in  which  the  magnetic 
needle  is  deflected;  and  also  deflects  it  one  way  when  it  passes 
above  the  needle  and  in  the  opposite  way  when  it  passes  below 
it.     This  fact  enables  us  to  very  greatly  intensify  the  action  of  the 

current  upon  the  magnetic 
needle,  by  putting  a  coil  of 
insulated  wire  about  the  com- 
pass, as  shown  in  Fig.  5.  With 
Flg'  5  such  an  arrangement,  all  the 

strands  of  wire  above  the  needle  are  carrying  the  current  in  one 
direction  and  all  those  below  in  the  opposite  direction.  They 
all,  therefore,  tend  to  deflect  the  needle  in  the  same  manner,  and 
the  effect  is  very  greatly  magnified ;  so  much  so,  that  such  an 
instrument  indicates  the  passage  of  currents  that  are  too  feeble  to 
be  detected  by  any  other  means.  It  is  called  a  Galvanometer. 

5.  Practical  Magnets. — The  electromagnet  is  much  more 
powerful  when,  instead  of  winding  the  wires  on  a  straight  bar  as  in 
Fig.  3,  page  93,  the  bar  is  bent  U  shape,  as  shown  in  Fig.  6- A, 
page  95,  for  in  this  position  both  ends  can  be  made  to  act  at  once 
upon  the  same  piece  of  iron,  and  they  can  attract  it  with  double, 
or  more  than  double  force.     It  is  also  found  that  the  wire  in  the 
middle  of  the  electromagnet  does  not  have  as  much  of  an  effect 
as  that  near  the  ends,  and  for  this  reason  the  wire  is  not  generally 
wound  on  the  middle  part,  but  only  on  the  ends,  as  shown 
in    Fig.    6-B.     Again,   it  is   ordinarily   advantageous,   from  the 
manufacturing  standpoint,  to  make  the  iron  core  of  a  magnet  in 
sections,  afterwards  fastening  them  together,  as   shown  in  Fig. 
6-C.     The  sections  "  H  I "  can  then  be  wound  with  the  wire, 
just  like  thread  is  wound  on  a   spool,  securing  great  efficiency 
as  well  as  ease  in  manufacture  (Fig.  6-D). 

94 


Such  electromagnets,  when  of  large  size  and  actuated  by 
powerful  currents,  are  of  tremendous  power,  and  will  lift  masses 
of  iron  weighing  tons. 

6.  If  a  piece  of  soft  iron,  i.  e.,  an  armature  (paragraph 
3-B,  page  92)  be  placed  between  the  poles  of  a  conveniently 

H  I  H  I 


Fig.  7 


shaped  magnet,  as  shown  in  Fig.  7,  the  piece  of  soft  iron  is  also 
caused  to  become  magnetic.  North  polarity  is  induced  in  the 
end  near,  or  in  contact  with,  the  south  pole,  and  vice  versa.  If 
the  position  of  the  armature  is  reversed,  so  that  the  end  "A"  is 
nearest  the  south,  and  "B"  nearest  the  north  pole  of  the  magnet, 
then  the  armature  reverses  its  polarity,  so  as 
to  always  present  its  south  end  to  the  north 
end  of  the  controlling  ("field")  magnet.  This 
it  does,  even  though  the  reversal  of  ends  is 
very  rapid,  such  as  would  result  from  fixing  a 
shaft  into  the  armature  at  "  J,"  and  rotating  it 
rapidly  in  the  direction  shown  by  the  arrows. 

We  have  seen  (paragraph  3-B,  page  92)  how  passing  an 
electric  current  through  wire  wound  upon  a  soft  iron  bar  is  capable 
of  causing  it  to  become  magnetic.  The  reverse  of  this  proposition, 
namely,  the  induction  of  an  electric  current  in  the  wire  about  an 
iron  bar  by  causing  the  bar  to  become  magnetic,  is  also  true  with 
certain  limitations.  Take  such  a  bar  wound  with  wire  ("A,"  Fig. 
8,  page  96)  and  connect  the  ends  of  the  wire  with  a  galvanometer 
(the  construction  of  which  is  explained  in  paragraph  4,  page  94), 
so  that  we  will  know  whenever  a  current  passes.  Now  cause 
the  end  of  the  bar  to  approach  the  live  electromagnet  "  B,"  Figt 
8.  All  the  time  it  is  approaching  "B,"  the  galvanometer  shows 
that  an  electric  current  is  passing.  When  the  movement  is 
stopped,  the  current  stops. 


95 


If  the  movement  be  reversed,  that  is,  if  the  wire-wound  bar 
be  moved  away  from  the  magnet,  the  galvanometer  will  again 
show  that  a  current  is  passing,  but  in  the  opposite  direction. 


Fig.  8 


The  reason  the  current  is  set  up  (induced)  in  the  wire 
around  the  iron  bar  is  because  the  iron  bar  is  caused  to  become 
magnetic  as  it  approaches  the  live  magnet  (paragraph  6,  page 
95),  and  loses  this  induced  magnetism  as  it  is  withdrawn;  and 
there  is  a  nautral  law  that  any  change  in  the  magnetic  condition 
of  an  iron  core  will  induce  an  electric  current  in  wire  around  it. 

It  may  be  argued  that  the  result  is  not  an  electric  current, 
but  a  series  of  electric  pulsations.  That  is  perfectly  true;  but  if 
the  pulsations  are  sufficiently  frequent,  through  rapid  rotation  of 
the  armature  shaft,  they  produce  similar  enough  effects  to  the 
steady  flow  of  a  battery  current  to  be  available  for  most  purposes. 

But  the  currents  induced  in  the  armature  do  more  than 
pulsate.  If  the  ends  of  the  armature  wire  are  connected  with  a 
galvanometer,  and  the  armature  slowly  revolved  so  that  the  move- 
ments of  the  needle  can  be  watched,  the  needle  will  be  found 
to  swing  first  to  the  east,  then  to  the  west,  then  east,  then  west 
again,  changing  direction  with  each  half  revolution  of  the  armature. 
If  the  end  of  the  galvanometer  needle  should  be  equipped  with  a 


Fig.  9 


pen,  so  that  it  could  make  a  mark  on  a  paper  tape  moved  steadily 
beneath  it  by  clockwork,  the  tracing  that  would  be  obtained  by 
this  experiment  would  look  like  Fig.  9. 


96 


In  this  illustration,  the  straight  line  "  A  B"  is  the  mark  the  pen 
would  make,  if  the  paper  were  moved  forward  with  the  needle 
at  rest  and  pointing  to  zero,  or  north.  The  wavy  line  "  C  D  "  is 
the  mark  made  by  the  needle  when  such  a  current,  continually 
reversing  its  direction,  is  sent  through  the  apparatus.  Such  a 
current  is  called  an  Alternating  Current. 

But  it  is  evident  from  what  has  already  been  said  (paragraph 
4,  page  94)  that  such  an  alternating  current  would  not  do  to 
energize  the  field  magnet.  In  order  to  maintain  the  constant 
polarity  of  the  field  magnet,  the  current  supplying  it  with  energy 
must  be  in  one  direction,  like  the  battery  current.  This  is  called  a 
Direct  Current.  The  alternating  current  induced  in  the  armature 
is,  therefore,  rectified  or  changed  into  a  direct  current  by  means 
of  the  Commutator  (Fig.  1 0). 


The  commutator  consists  of  a  cylinder  of  hard  fiber  or 
rubber,  covered  with  copper,  and  mounted  on  the  same  shaft 
which  drives  the  armature.  The  copper  is  cut  lengthwise  into 
two  sections  ("A"  and  "B,"  Fig.  1 0).  These  are  firmly  attached 
to  the  surface  of  the  hard  fiber  very  close  together,  but  not  touch- 
ing; that  is,  they  are  insulated  from  each  other  by  the  fiber  which 
carries  them.  One  end  of  the  armature  wire  is  connected  with 
section  "A,"  the  other  with  section  "B." 

The  current  is  taken  off  of  the  commutator  for  use  by  "C'* 
and  "D"  (Fig.  10),  called  Brushes.  Now,  as  the  commutator 
revolves  with  the  shaft,  while  the  brushes  remain  stationary,  the 
section  "  A  '*  is  in  contact  with  brush  "  C  "  for  half  a  revolution, 
then  with  brush  "  D  "  for  the  other  half.  The  same  thing  happens 
to  section  "B."  Therefore,  the  effect  of  the  commutator  is  to 
change  the  alternating  armature  current  into  a  Direct  Current, 
and  the  tracing  which  the  record  galvanometer  will  make  on  the 

97 


tape,  when  it  receives  the  current  from  the  dynamo  equipped 
with  the  commutator,  is  shown  in  Fig.  1 1 . 


Fig.  11 

The  alternating  current  would  fire  electric  fuzes  as  well  as 
the  direct  current;  but  if  it  were  not  converted  into  a  direct 
current  as  it  is,  we  would  either  have  to  energize  the  field  magnet 
with  a  battery  or  use  a  permanent  magnet.  With  the  present 
arrangement,  we  simply  lead  the  rectified  current  from  the 
armature  through  the  wire  on  the  field  magnet,  which  is  thus 
energized  by  the  current  from  its  own  armature.  At  the  start, 
the  very  slight  residual  magnetism  which  is  retained  by  the  field 
magnet  (see  note  J,  paragraph  3,  page  92)  is  sufficient  to  set 
up  a  feeble  current  in  the  armature.  This  in  turn  makes  the  field 
magnet  stronger,  and  the  stronger  field  magnet  develops  a  stronger 
current  in  the  armature.  Thus  the  machine  "builds  up,"  as  it  is 
called,  until  after  a  few  revolutions  it  is  working  at  its  full  power. 
You  can  notice  this  when  you  push  down  the  rack  bar  of  a 
"push  down"  blasting  machine.  The  first  part  of  the  stroke  is 
easy,  but  after  the  armature  has  made  a  few  revolutions,  it  pushes 
quite  hard,  because  the  magnet  has  become  strong  and  pulls  back 
on  the  armature,  tending  to  resist  our  efforts  to  turn  it. 

The  dynamo  just  described,  which  is  used  in  most  American 
blasting  machines,  is  one  of  the  simplest  and  earliest  forms  of 
dynamo.  Those  used  for  generating  powerful  currents  for 
electric  lighting,  etc.,  are  more  complicated,  and  more  efficient 
electrically  than  those  made  on  this  simple  design;  that  is,  if  the 
blasting  machine  dynamo  were  constructed  on  modern  principles, 
it  would  take  less  power  for  the  same  output  of  current  or  give 
greater  output  with  the  same  amount  of  power,  whichever  way 
one  chooses  to  look  at  it.  But,  for  the  purposes  to  which  a  blast- 
ing machine  is  put,  considerations  of  simplicity  outweigh  this  kind 
of  efficiency.  Blasters  would  rather  exert  a  little  more  muscle  in 
operating  the  blasting  machine  than  pay  for  the  increased  cost 
of  repairs  to  a  more  modern  dynamo,  not  to  mention  the  increased 

98 


first  cost.  Indeed,  it  is  doubtful  if  a  more  satisfactory  blasting 
machine  could  be  reasonably  asked  for  than  the  ordinary  "push 
down"  blasting  machine  just  as  it  is  now  made.  Certainly  no 
other  piece  of  electrical  machinery  would  stand  the  misuse  to 
which  many  of  these  blasting  machines  are  subjected  in  practice, 
and  still  continue  to  do  good  work,  day  after  day  and  year  after 
year,  as  so  many  of  them  do  in  spite  of  it  all. 

Let  us  now  dissect  an  ordinary  "push  down"  blasting 
machine,  as  a  sort  of  review,  and  see  how  these  electrical  prin- 
ciples apply.  Fig.  1 2  is  a  three  post  blasting  machine  while  Fig. 
1  3  shows  a  two  post  blasting  machine.  Note  the  field  magnets. 


FIG.  12 


FIG.  13 


"  8 "  and  "  9  "  with  their  winding  of  coarse  wire.  In  both  figures 
the  armature  "16"  can  be  seen  with  its  winding  of  finer  wire. 

Note  the  brushes  "  20,"  bearing  on  the  commutator  just  as 
already  described,  and  see  where  the  ends  of  the  armature  wire 
are  soldered,  each  to  its  respective  commutator  section.  On  the 
other  side  is  the  rack  and  pinion  ratchet  movement,  by  which  the 
downward  thrust  of  the  rack  bar  "  1 "  imparts  rotary  movement  to 
the  armature.  This  is  so  simple  that  anyone  can  see  at  a  glance 
how  it  works,  and  it  need  not  be  dealt  with  here. 

There  is  one  part  of  the  blasting  machine  simple,  but  of 
great  importance,  which  has  not  yet  been  taken  up,  and  that  is 

99 


the  "shunt,"  sometimes  called  the  "circuit  breaker."  This  is  the 
brass  contrivance  "4"  (Figs.  12  and  13)  placed  in  the  bottom  of 
the  box.  It  is  really  nothing  but  a  brass  spring  which  makes 
contact  with  the  bridge  "  5,"  when  in  its  normal  position,  the 
parts  which  come  in  contact  being  covered  with  platinum,  so  that 
they  will  remain  bright  and  make  a  good  electrical  connection. 

The  function  of  this  shunt  is  as  follows:  The  spring  "4," 
called  the  "contact  spring,"  is  connected  by  means  of  a  piece  of 
heavy  copper  wire  to  one  of  the  binding  posts,  "26,"  represent- 
ing one  pole  of  the  dynamo;  the  bridge  is  connected  with  the  other 
binding  post,  representing  the  other  pole  of  the  dynamo,  so  that 
when  the  contact  spring  is  up  in  contact  with  the  bridge  a  short, 
easy  circuit  called  a  "shunt,"  of  practically  no  resistance,  is  offered 
for  the  electric  current  to  pass  from  one  pole  to  the  other — in  the 
language  of  the  electrician,  the  dynamo  is  "short  circuited." 
While  the  rack  bar  is  being  pushed  down,  the  blasting  machine 
is  "building  up,"  the  current  generated  passing  across  the  shunt, 
so  that  by  the  time  the  rack  bar  is  near  the  bottom  of  the  stroke 
the  dynamo  is  working  at  its  maximum.  When  the  rack  bar 
strikes  the  contact  spring,  however,  separating  it  from  the  bridge, 
the  short  circuit  is  broken,  and  the  current  of  the  dynamo  has 
now  no  other  way  to  pass  from  one  pole  to  the  other  except  by 
flowing  out  through  the  electric  fuze  circuit,  which  it  does  just  at 
the  instant  when  it  is  at  its  maximum  strength.  The  fine  platinum 
bridge  wire  in  each  electric  fuze  heats  up  almost  instantly, 
causing  them  all  to  detonate  at  practically  the  same  time. 

Were  it  not  for  the  shunt,  operating  as  just  described, 
current  from  the  dynamo  would  begin  to  flow  through  the  electric 
fuzes  as  soon  as  we  started  to  push  down  the  rack  bar.  It 
would  be  a  very  weak  current  at  first,  gradually  increasing  with 
the  building  up  of  the  blasting  machine.  Such  a  current  is  not 
well  adapted  to  fire  a  number  of  electric  fuzes  simultaneously, 
because  it  is  impossible  to  make  all  of  exactly  the  same  degree  of 
sensitiveness,  and  with  the  gradually  increasing  current,  the  more 
sensitive  electric  fuzes  would  fire  first,  breaking  the  circuit  and 
causing  the  less  sensitive  ones  to  miss.  By  employing  the  shunt, 

100 


on  the  other  hand,  no  current  is  sent  out  from  the  blasting 
machine  until  there  is  ample  power  to  fire  even  the  least  sensitive. 

The  three  post  blasting  machine  contains  an  ingenious  device 
for  increasing  by  approximately  50  per  cent,  the  number  of  electric 
fuzes  that  the  two  post  blasting  machine  would  be  able  to  fire. 

When  it  is  desired  to  take  advantage  of  the  three  post 
feature  of  such  a  blasting  machine,  the  electric  fuze  circuit  is 
arranged  as  shown  on  page  34.  Three  leading  wires  are  used, 
which  really  divide  the  blasting  circuit  into  two  separate  circuits. 
The  great  increase  in  efficiency  is  brought  about  by  equipping 
the  contact  spring  with  both  an  upper  and  a  lower  contact  and 
arranging  it  so  that  it  will  throw  the  full  power  of  the  dynamo 
first  into  one  circuit  and  then  into  the  other.  While  the  two 
circuits  do  not  really  fire  simultaneously,  the  interval  between  them 
is  so  extremely  short  that  we  hear  only  one  explosion.  If  it  were 
not  very  short,  the  wires  in  one  circuit  would  probably  be  broken 
by  flying  fragments  of  rock  thrown  out  by  the  explosion  of  the 
charges  in  the  other  circuit. 

By  connecting  one  of  the  two  leading  wires  to  the  middle 
binding  post  and  the  other  to  either  of  the  outside  ones,  as  is  also 
shown  on  page  34,  a  three  post  blasting  machine  may  be  used 
as  a  two  post  blasting  machine  whenever  the  number  of  electric 
fuzes  to  be  fired  does  not  exceed  the  capacity  of  a  two  post 
blasting  machine  of  that  particular  size.  The  great  advantage  in 
having  a  three  post  blasting  machine  is  that  when  difficult  con- 
ditions arise,  which  would  ordinarily  require  a  larger  blasting 
machine,  they  can  often  be  met  in  a  very  satisfactory  manner 
merely  by  laying  another  leading  wire  and  making  use  of  the 
three  post  feature. 

Nothing  has  been  said  thus  far  regarding  the  "pull  up" 
blasting  machine.  It  is  not  necessary  to  discuss  it  at  any  great 
length,  since  it  is  different  from  the  "push  down"  blasting  machine 
only  in  the  mechanical  detail,  of  using  the  upward  movement  of 
the  handle  as  the  driving  stroke  instead  of  the  downward  one. 
The  mechanical  application  of  the  ratchet  principle  is  slightly 
different,  but  not  so  much  so  that  it  cannot  be  seen  at  a  glance. 
The  construction  of  the  dynamo  is  identical. 


101 


CHAPTER  2 

Effective  Use  of  Electric  Blasting 
Apparatus 

iLMOST  anyone  can  use  electric  blasting  supplies, 
and  obtain  good  results,  merely  by  following  gen- 
eral instructions.     However,  the  knowledge  of  the 
principles  underlying  their  action,  which  will  have 
been  gained  by  reading  the  previous  chapter,  will 
be  a  great  aid  in  obtaining  their  highest  possible 
efficiency.     Again,    when  the  man  who    under- 
stands   the   principles  encounters   difficulties,   he 
knows  how  to  overcome  them,  while  the  man  who  does  not 
understand  has  to  be  helped  out  of  his  troubles. 

One  who  knows  the  internal  construction  of  the  blasting 
machine,  and  has  learned  from  examination  and  study  what  a 
nice  piece  of  mechanism  it  really  is,  will  generally  take  good  care 
of  it.  Keeping  it,  when  not  in  use,  in  a  clean,  dry  place  is  the 
first  thing  you  can  do  to  help  the  blasting  machine  help  you. 
Down  in  a  wet  tunnel  or  mine  is  not  a  good  place  to  store  such 
an  instrument,  and  if  it  must  be  used  in  such  places,  as  is  often 
the  case,  and  it  cannot  be  taken  to  the  surface  between  times 
(which  is  sometimes  the  case),  a  water  tight  closet  or  box  should 
be  built  for  it,  in  as  good  a  location  as  can  be  found.  Remember 
that  the  case  is  only  wood,  and,  if  saturated  with  water,  may 
swell  and  put  the  internal  parts  out  of  adjustment.  Occasionally 
rubbing  a  little  oil — preferably  thick  cylinder  oil — into  the  grain 
of  the  wood  will  help  it  to  resist  the  water.  The  best  way  to 
apply  the  oil  is  by  rubbing  the  box  with  a  greasy  rag. 

When  you  use  the  blasting  machine,  try  to  find  a  clean, 
level  place  to  stand  it  on,  such  as  a  dry  plank,  so  that  the  bottom 

will  not  be  all  wet  when  you  put  it  away  after  using. 

• 

103 


After  the  principles  of  its  operation  are  thoroughly  under- 
stood, the  efficiency  of  the  blasting  machine  may  be  kept  up  to 
the  maximum,  by  occasional  inspection  and  care  of  the  internal 
parts,  although  they  are  so  constructed  as  to  seldom  require  much 
care. 

The  first  thing  to  be  done  in  caring  for  the  dynamo  and 
working  parts  is  occasional  oiling.  And  here  much  judgment 
should  be  used,  for  too  much  oil  is  worse  than  none  at  all.  The 
only  places  that  need  it  are  the  bearings  of  the  armature  shaft 
and  of  the  armature  pinion.  The  other  iron  parts  that  can  be 
reached  should  be  wiped  off  with  a  greasy  rag  to  prevent  them 
from  rusting,  more  particularly  the  faces  of  the  armature  (not  the 
wire).  No  oil  should  be  used  on,  or  allowed  to  come  in  contact 
with,  the  brushes  and  commutator,  nor  with  the  contact  spring 
and  its  contact  points.  For  this  reason,  the  amount  of  oil  used 
in  any  part  of  the  blasting  machine  should  be  small,  or  it  will 
afterwards  flow  over  places  where  it  is  not  wanted.  This  is 
especially  the  case  with  the  rack  bar.  Too  much  oil  here  will 
inevitably  flow  down  upon  the  contact  spring  and  its  contact 
points,  and  cause  a  poor  electrical  connection  with  the  bridge. 
In  fact,  a  poor  electrical  connection  at  this  point  is  one  of  the 
most  common  causes  of  the  poor  work  and  erratic  behavior 
of  the  blasting  machine.  Wiping  off  the  rack  bar  and  guide 
rod  with  a  greasy  rag  will  give  them  all  the  lubrication  they 
require. 

The  friction  incident  to  ordinary  usage  will  generally  be 
sufficient  to  keep  the  surfaces  bright  where  the  brushes  bear  upon 
the  commutator,  unless  some  misguided  person  has  oiled  them. 
In  that  case,  the  oil  should  be  removed  as  well  as  possible  by 
thorough  cleaning  with  a  rag  saturated  with  gasoline.  If  the 
brushes  seem  to  be  too  rapidly  wearing  into  the  commutator,  so 
that  they  absolutely  demand  some  kind  of  lubricant,  use  a  little 
graphite  taken  from  a  soft  lead  pencil.  After  removing  the  oil 
by  the  use  of  gasoline,  be  sure  that  all  the  gasoline  and  its  vapor 
are  out  of  the  box  before  closing  it  up,  or  the  vapor  may  after- 
wards ignite  and  blow  the  box  apart. 

104 


The  contact  points  on  the  contact  spring,  bridge,  etc.,  may 
be  brightened  up  occasionally  with  very  fine  emery  cloth,  but  be 
careful  how  you  use  emery  cloth  or  paper  in  and  about  the  machine, 
for  the  dust  and  finer  particles  from  it,  if  they  get  into  the  working 
parts,  will  cause  them  to  wear  out  rapidly.  Also,  when  you  use 
emery  cloth  on  the  platinum  contact  points,  remember  that  all  you 
are  aiming  to  do  is  to  remove  any  possible  dirt  or  oxide  from  them, 
and  do  not  go  about  it  so  vigorously  as  to  grind  off,  after  a  few 
such  inspections,  all  of  the  platinum  points  themselves.  There  is 
a  very  hot  flash  when  the  contact  spring  leaves  the  upper  contact, 
and  if  the  parts  which  touch  are  not  of  platinum  (that  is,  if  the 
platinum  has  all  been  ground  away  so  that  only  brass  touches)  the 
brass  quickly  becomes  oxidized,  and  fails  to  make  a  good  contact. 

The  joints  connecting  together  the  various  electric  fuzes, 
leading  wires,  connecting  wire,  etcf,  that  are  to  comprise  the  circuit 
often  do  not  receive  as  much  attention  as  they  should.  It  is  true 
that  mere  contact  between  perfectly  clean  wires  is  sufficient  to 
permit  the  passage  of  the  current,  but  it  is  almost  impossible  to 
get  them  perfectly  clean,  and  the  joint  should,  therefore,  be  made 
in  such  a  manner  as  to  press  together  a  considerable  amount 
of  the  wire,  after  it  has  been  cleaned  as  thoroughly  as  possible. 
This  preliminary  cleaning  or  scraping  should  never  be  neglected. 
There  is  sure  to  be  tar  or  grease  present  from  the  water  proofing 
material  used,  as  well  as  oxides,  dirt  and  all  manner  of  foreign 
material  that  may  have  adhered  to  the  wire. 

There  are  many  methods  of  making  joints,  some  of  them 
good  and  some  bad.  The  one  generally  recommended  is  made 
as  shown  in  Fig.  1  7. 


Fig.  17 


Another  good  way,  if  one  has  pliers  to  finish  up  the  joint 
with,  is  that  shown  in  Fig.  1 8,  page  1 06.  This  is  made  the  same 
as  in  the  previous  figure,  but  afterwards  the  ends,  which  are  left 
long  for  that  purpose,  are  twisted  together. 


105 


It  is  much  easier  to  connect  together  wires  of  the  same  size 
than  where  the  sizes  differ,  such  as  joining  the  leading  and  electric 
fuze  wires  together.  For  this  purpose,  a  joint  like  that  shown  in 


Fig.  18 

Fig.  2 1  is  good,  the  spring  of  the  thick  wire  keeping  up  a  tension 
on  the  small  wire,  and  causing  it  to  make  a  good  contact.  It  is 
difficult  to  make  a  nice  joint  under  such  circumstances,  but  it  can 
be  made  good  electrically  if  the  wires  are  first  thoroughly  cleaned. 
Joints  in  the  leading  wire,  when  they  must  be  made,  should 
be  made  with  special  care.  Those  in  the  connecting  and  electric 
fuze  wires,  as  a  rule,  only  have  to  do  service  for  a  few  minutes 
or  hours ;  but  those  in  the  leading  wire  will  be  there  while  the 
leading  wire  lasts,  and  if  poorly  made  will  give  trouble  long  after 
their  location  is  forgotten.  Fig.  1 7,  page  1 05,  shows  how  such 
joints  should  be  made.  The  method  is  just  the  same  as  that 
recommended  for  the  electric  fuze  wires,  only  these  joints  should 
be  about  2  or  3  inches  in  length.  It  pays  to  have  joints  in 
the  leading  wire  soldered.  Some  of  the  most  peculiar  and  erratic 
troubles  are  due  to  defective  joints  in  the  leading  wire,  which 


Fig.  21 


worked  satisfactorily  for  a  number  of  shots,  but  afterwards  became 
bad  through  corrosion  having  formed  between  the  contact  surfaces. 
The  electrical  condition  of  such  a  joint  is  liable  to  change  on  the 
slightest  movement  of  the  wire,  good  one  minute  and  bad  the  next, 
and  for  that  reason  making  a  trouble  difficult  to  locate. 


106 


Of  course,  wherever  a  joint  has  been  made  the  wire  will  be 
bare  of  insulation  at  that  point,  and  the  question  is  often  asked 
whether,  in  such  cases,  it  is  always  necessary  to  use  insulating 
tape  for  covering  the  bare  places.  Where  these  joints  are  in  the 
leading  wire,  and  especially  where  they  are  in  electric  fuze  or 
connecting  wire  which  is  to  be  inside  of  the  bore  hole  and  covered 
with  tamping,  they  should  be  taped.  If  the  joints  are  not  to  go 
underground,  it  is  not  absolutely  necessary  to  tape  them,  and  it 
will  be  sufficient  if  they  are  elevated  and  kept  off  the  ground,  or 
from  touching  anything,  by  placing  blocks  of  wood  under  the  wire 
near  the  joint.  Joints  in  the  leading  wire  can  be  treated  in  this 
way  also,  thus  avoiding  the  necessity  of  taping  them ;  but  it  is  a 
nuisance  to  have  to  go  all  over  the  line  blocking  up  bare  places 
before  a  blast,  when  the  whole  trouble  could  be  avoided  by  a  few 
turns  of  insulating  tape.  In  fact,  a  well  made,  soldered  and  taped 
joint  puts  the  leading  wire  in  almost  as  good  condition  as  when 
new,  while  a  few  questionable  joints  are  sure  at  some  time  to  be 
a  source  of  annoyance,  delay  and  danger.  It  is  best  not  to 
have  any  more  joints  in  the  circuit  than  are  absolutely  necessary. 
Joints  are  especially  objectionable  when  they  have  to  be  lowered 
into  the  bore  hole  because  the  electric  fuze  wires  are  too  short. 
The  electric  fuze  wires  ought  to  be  long  enough  to  prevent 
the  necessity  of  making  this  kind  of  joints.  It  is  even  better  to 
have  them  long  enough  to  connect  directly  with  the  wire  of  the 
electric  fuze  in  the  adjoining  bore  hole,  thus  avoiding  the  use  of 
connecting  wire  as  well  as  saving  time.  But  when  you  do  require 
connecting  wire,  don't  use  old  electric  fuze  wire  that  is  full  of 
joints  and  bruises  from  having  already  been  through  a  blast.  Use 
new  connecting  wire.  The  use  of  old,  damaged  electric  fuze  or 
connecting  wire  is  the  worst  kind  of  false  economy.  No  expe- 
rienced contractor  needs  to  be  told  how  expensive  it  is  to  have  a 
long  period  of  delay  after  the  men  have  been  ordered  away  from 
the  work,  while  the  blaster  pokes  around,  looking  for  the  "reason 
why  the  shot  did  not  go  off,"  all  men,  horses  and  machinery 
idle  meanwhile. 

107 


Preparing  the  primer  is  really  one  of  the  most  important  steps 
in  all  blasting  operations.  And  yet,  how  frequently  we  find  this 
work  entrusted  to  one  of  the  least  skilled  among  the  workmen. 
It  ought  to  be  done  in  the  safest  suitable  place  that  can  be  found, 
and  it  should  also  be  done  in  the  manner  which  is  calculated  to 
secure  the  best  results.  Yet  both  of  these  considerations  are 
frequently  violated,  and  the  priming  is  done  in  the  thawing  house 
or  magazine  where  an  accidental  explosion  would  be  certain  to 
cause  widespread  disaster,  and  is  also  done  in  a  manner  just  the 
opposite  to  that  recommended  by  the  manufacturers  of  explosives 
and  blasting  supplies. 

The  most  common  way  of  making  a  primer  is  that  shown 
in  Fig.  24.  That  is,  the  electric  fuze  is  inserted 
into  some  part  of  the  cartridge  of  dynamite  and 
kept  from  pulling  out  by  taking  one  or  more  half 
hitches  around  the  cartridge.  But  this  is  not  the 
method  recommended  by  the  manufacturers.  One 
trouble  with  this  method  is  that  all  the  strain  comes 
at  the  two  points  marked  ''A,"  where  one  of  the  two 
wires  bends  sharply  around  the  other.  Should  the 
strain  be  severe  enough  to  cause  the  wires  to  cut 
through  the  insulation  at  this  point,  it  will  furnish  the 
"shorter  or  easier  path  for  the  current"  referred  to 
in  paragraph  2,  page  91,  and  the  current  will 
escape  across  the  short  circuit,  without  going 
through  the  electric  fuze,  causing  that  particular 
bore  hole  to  miss. 

In  spite  of  the  recommendations  of  the  manu- 
facturers, however,  it  is  very  seldom  one  finds  a 
blaster  making  primers  in  the  right  way  (see  Fig.  25, 
page  109),  the  reason  generally  given  being  that  "it  is  too  much 
trouble  to  hunt  up  strings  and  tie  them."  Of  all  operations 
where  results  justify  a  little  extra  trouble,  none  can  exceed  in 
importance  the  making  of  the  primer,  for  upon  this  depends  the 
success  of  the  entire  blast.  Of  course,  it  takes  a  little  longer 
to  make  primers  in  the  proper  way  than  it  does  by  the  half  hitch 


Fig.  24 


108 


method,  but  the  extra  time  is  well  spent,  and  it  should  be  borne 
in  mind  that  it  is  the  time  of  one  man,  while  the  time  spent  in 
"hunting  trouble"  is  the  combined  time  of  all  the  men,  horses 
and  machinery.  There  never  yet  was  a  cheap  misfire. 

Where  should  the  primers  be  made  up? 
It  is  necessary  that  a  location  be  selected  in  cold 
weather  where  they  will  not  chill  during  and  after 
the  process ;  therefore,  some  kind  of  a  heated  build- 
ing is  almost  of  necessity  selected.  But  it  should 
not  be  one  in  which  an  accidental  explosion  would 
carry  with  it  the  entire  contents  of  a  magazine  or 
thawing  house. 

It  is  the  warmth  of  a  steam  heated  magazine 
or  thawing  house  which  in  winter  always  makes 
them  tempting  spots  for  this  work.  The  blacksmith 
will  not  tolerate  the  process  in  his  domain,  and  still 
less  will  the  "boss"  tolerate  it  in  his  office;  there- 
fore, the  poor  fellow  who  does  the  work  seeks  out 
the  only  warm  spot  open  to  him. 

There  really  ought  to  be  a  separate  small 
building,  heated  by  exhaust  steam  or  hot  water,  set 
apart  for  this  purpose,  and  in  that  case  a  closet  in 
one  corner  might  be  used  to  store  the  blasting 
machine,  leading  wire  and  other  non-explosive 
goods.  Even  a  small  supply  of  blasting  caps  and 
electric  fuzes  might  be  allowed  there,  provided  their  number  be 
kept  so  small  that  they  would  not,  in  themselves,  represent  a  con- 
siderable quantity  of  explosive  material.  But  strict  rules  should 
be  enforced  to  prevent  the  men  from  using  this  building  as  a 
lounging  place  or  a  place  in  which  to  eat  their  lunches  and  smoke. 
The  Du  Pont  Company  publishes  and  supplies  a  set  of  rules  to 
be  tacked  up  in  magazines,  and  many  of  these  rules  would  be 
applicable  here.  They  are  printed  upon  muslin,  and  are  to  be 
signed  by  the  superintendent  and  can  be  obtained  gratis  by 
writing  for  them  to  our  nearest  branch  office.  (See  list  on  the 
back  of  this  catalogue.) 

109 


After  the  primers  are  made,  they  should  be  kept  in  a  box, 
equipped  with  a  tight  fitting  hinged  cover  to  prevent  the  possible 
entrance  of  sparks.  This  box  should  be  kept,  until  the  primers 
are  required,  in  the  priming  house,  at  a  temperature  of  between 
70°  F.  and  80°  F.,  so  that  they  will  not  become  frozen  or  chilled. 

The  primer  especially  must  be  well  thawed,  and  in  the  best 
possible  condition.  If  the  bore  holes  are  wet,  it  is  well  to  seal 
up  the  place  where  the  detonator  has  been  inserted  in  the  cartridge 
by  means  of  soap,  tar  or  some  other  water  proofing  material, 
since,  if  the  explosive  immediately  surrounding  the  detonator  is 
impaired  in  any  way,  it  is  likely  to  cause  a  failure  or  inferior  work 
of  the  entire  blast. 

Once  the  loading  has  commenced,  a  blast  should  be  loaded 
and  fired  as  expeditiously  as  possible.  Many  things  may  happen 
to  detract  from  the  efficiency  of  a  charge  after  it  is  loaded,  and 
the  chances  increase  with  every  minute  that  elapses  between 
loading  and  firing.  The  dynamite  may  freeze  if  the  rock  or 
ground  is  cold  enough,  water  may  work  its  way  into  the  electric 
fuzes,  and  the  insulation  on  the  wires  may  be  affected  by  moisture, 
so  that  the  leakage  of  current  will  cause  one  or  more  charges  to 
miss. 

The  blasting  machine  should  always  be  operated  with  as 
much  force  as  the  operator  can  exert.  Try  especially  to  finish 
the  last  part  of  the  stroke  with  your  full  power,  for  when  the 
rack  bar  nears  the  end  of  the  stroke  it  will  push  quite  hard,  tend- 
ing to  check  the  movement,  and  yet  the  end  of  the  stroke  is  the 
most  important  of  all.  It  takes  a  man  with  considerable  strength, 
and  with  some  skill  to  get  the  full  force  out  of  a  large  blasting 
machine. 

It  is,  of  course,  obvious  that  no  more  current  is  required  to 
fire  stronger  electric  fuzes  than  weaker  ones.  Those  with  very 
long  wires,  however,  do  require  more  current,  for  the  small  copper 
wire  which  is  used  has  some  resistance.  An  electric  fuze  with 
26  foot  wires  would  take  about  twice  as  strong  a  current  to  fire 
it  as  it  would  if  the  current  could  be  delivered  close  to  the  fuze 
cap,  instead  of  having  to  go  through  the  26  foot  wires. 

110 


Many  careful  blasters  have  long  wished  for  some  means  to 
guard  against  misfires  by  which  the  blasting  machine  and  the 
individual  electric  fuzes  could  be  tested,  before  attempting  to  use 
them.  If  they  could  always  be  used  just  as  they  come  from  the 
factory,  without  being  subjected  to  the  unfavorable  conditions 
they  so  often  meet  with  in  transportation  and  storage,  it  is  probable 
that  there  would  be  little  need  for  testing  because  every  manufac- 
turer carefully  tests  his  goods  before  sending  them  out.  The 
Du  Pont  Company  tests  them  twice.  Electric  Fuzes  are  especially 
liable  to  damage  during  transportation  and  storage,  and  particularly 
so  if  they  are  stored  in  a  damp  place. 

The  Du  Pont  Rheostat  (see  page  55)  should  be  used  in 
testing  blasting  machines,  and  for  testing  electric  fuzes  and  the 
blasting  circuit  the  Du  Pont  Galvanometer  (see  page  43)  is 
recommended. 

A  test  with  almost  any  kind  of  testing  instrument  would  be 
sufficient  to  reveal  the  presence  of  a  broken  bridge  in  an  electric 
fuze  (see  illustration,  page  1 2),  which  is  indeed  the  most  usual 
defect.  But  it  will  not  reveal  those  electric  fuzes  which  are 
defective  through  a  short  circuit,  such  as  where  the  electric  fuze 
wires  are  not  insulated  from  each  other  within  the  electric  fuze 
cap,  or  have  accidentally  come  into  contact  after  having  been 
manufactured.  In  such  cases,  they  would  fail  to  fire,  of  course, 
because  the  current  would  follow  the  short  circuit  and  not  go 
through  the  bridge.  To  identify  electric  fuzes  defective  from  this 
cause,  it  is  necessary  to  have  some  form  of  instrument  which  will 
show  at  least  approximately  the  electrical  resistance.  The  Du 
Pont  Galvanometer  can  be  used  for  this  if  very  carefully  observed, 
but  a  "  Wheatstone  bridge "  is  better. 

When  testing  electric  fuzes,  they  should  always  be  placed 
in  such  a  position  that  if  one  of  them  should  happen  to  detonate 
accidentally  no  one  will  be  injured.  Placing  them  around  the 
corner  of  a  stone  wall  is  an  easy  and  safe  way,  or,  if  there  are 
but  a  few  of  them,  they  can  be  buried  under  a  foot  of  dry  sand. 
If  there  are  many,  so  that  the  total  amount  of  fulminate  is  consid- 

111 


erable,  the  particles  of  sand  themselves  would  become  projectiles 
capable  of  injuring  anyone  near  by. 

Of  course,  there  are  occasions,  as  for  instance  when  there 
has  been  a  misfire  and  it  is  necessary  to  locate  the  trouble,  when 
some  risk  must  be  taken,  even  to  making  use  of  the  galvanometer 
in  testing  electric  fuzes  that  are  loaded  in  bore  holes  with  explosives, 
and  often  in  such  locations  where  the  firing  of  the  charge  during 
the  test  would  be  disastrous  to  the  tester.  But  under  such  condi- 
tions, the  very  remote  danger  of  the  test  replaces  a  much  greater 
danger,  which  always  exists  whenever  a  blast  misfires,  and  the 
blaster  is  hunting  about  for  the  reason  why.  Under  such 
circumstances,  there  is  no  doubt  that  a  great  saving  in  the  total 
amount  of  risk  results  from  locating  the  trouble  with  accuracy 
and  celerity,  even  though  there  be  a  remote  risk  in  the  test  itself. 

But  the  chances  of  firing  an  electric  fuze  while  testing  are 
thousands  of  times  greater  when  an  ordinary  series  magneto 
telephone  bell  or  other  unsuitable  instrument  is  used. 

Several  persons  have  been  badly  injured  in  this  way  because 
they  not  only  made  use  of  an  improper  testing  instrument,  but 
neglected  to  place  the  electric  fuze  in  a  safe  location.  It  is 
remarkable  what  extensive  damage  the  flying  particles  of  copper 
from  one  of  these  electric  fuzes  are  capable  of  doing. 

The  current  from  a  magneto  bell  is  of  too  small  a  volume  to 
fire  an  electric  fuze  by  heating  its  bridge,  but  it  is  of  sufficient 
intensity  to  jump  across  small  gaps,  such  as  would  result  if  an 
electric  fuze  had  a  broken  bridge,  and  the  broken  ends  were 
very  close  to  each  other.  When  the  current  jumps  across  such 
a  gap,  a  spark  is  produced  which  is  often  sufficient  to  ignite  the 
fulminate.  Another  way  in  which  an  electric  fuze  might  become 
sensitive  to  the  current  from  a  magneto  bell  is  by  the  formation 
of  corrosion  between  the  ends  of  a  break,  such  as  where, 
through  the  entrance  of  moisture,  the  copper  wire  had  corroded 
off  the  platinum  bridge  at  one  of  the  soldered  joints.  Should 
the  electric  fuze  subsequently  dry  out,  it  may  show  a  resistance 
several  hundred  times  greater  than  normal,  and  would  be 
very  likely  to  fire  with  the  current  from  a  magneto  bell  while 

112 


there  would  be  very  little  likelihood  of  its  firing  with  the  weak 
current  from  a  suitable  testing  battery  like  that  in  the  Du  Pont 
Galvanometer. 

What  lulls  the  suspicion  of  a  blaster  who  tests  with  a 
magneto  (and  the  matter  is  mentioned  here  because  there  are 
many  who  do)  is  the  fact  that  he  is  often  able  to  test  a  great 
many  electric  fuzes  with  it  before  one  of  them  fires  in  the  testing 
process.  But  some  day  one  that  is  defective  in  the  manner  above 
described  is  encountered — and  then,  too  frequently,  it  means  a 
maimed  hand,  blindness  or  worse.  For  this  reason,  the  use  of 
any  kind  of  testing  current,  except  that  from  a  weak  battery  used 
in  connection  with  a  galvanometer,  or  Wheatstone  bridge,  is  most 
earnestly  condemned,  and  further,  the  electric  fuzes  should  be 
placed  in  some  location  where  they  will  do  no  harm  if  one  should 
explode.  When  the  test  of  a  loaded  bore  hole  must  be  made, 
and  it  is  impracticable  to  attach  the  leading  wires  and  test  from  a 
safe  distance,  the  test  should  be  undertaken  with  the  full 
recognition  that  it  is  a  risk,  even  though  a  remote  one,  when  a 
suitable  instrument  is  used,  and  no  one  but  the  tester  himself 
should  be  exposed  to  the  risk. 


113 


Precautions  to  be  Observed  in  General 
with  Regard  to  Explosives 

DON'T  forget  the  nature  of  explosives,  but  remember  that  with 
proper  care  they  can  be  handled  with  comparative  safety. 

DON'T  smoke  while  you  are  handling  explosives,  and  DON'T 
handle  explosives  near  an  open  light. 

DON'T  shoot  into  explosives  with  a  rifle  or  pistol,  either  in  or  out  of 
a  magazine. 

DON'T  leave  explosives  in  a  field  or  any  place  where  stock  can 
get  at  them.  Cattle  like  the  taste  of  soda  and  saltpeter  in 
explosives,  but  tbe  other  ingredients  would  probably  make 
them  sick  or  kill  them. 

DON'T  handle  or  store  explosives  in  or  near  a  residence. 

DON'T  leave  explosives  in  a  wet  or  damp  place.  They  should  be 
kept  in  a  suitable,  dry  place,  under  lock  and  key,  and 
where  children  or  irresponsible  persons  cannot  get  at  them. 

DON'T  explode  a  charge  to  chamber  a  bore  hole  and  then  imme- 
diately reload  it,  as  the  bore  hole  will  be  hot,  and  the 
second  charge  may  explode  prematurely. 

DON'T  do  tamping  with  iron  or  steel  bars  or  tools.  Use  only  a 
wooden  tamping  stick  with  no  metal  parts. 

DON'T  force  a  primer  into  a  bore  hole. 

DON'T  explode  a  charge  before  everyone  is  well  beyond  the 
danger  zone  and  protected  from  flying  debris.  Protect 
your  supply  of  explosives  also  from  danger  from  this  source. 

DON'T  hurry  in  seeking  an  explanation  for  the  failure  of  a  charge 
to  explode. 

DON'T  drill,  bore  or  pick  out  a  charge  which  has  failed  to  explode. 
Drill  and  charge  another  bore  hole  at  least  two  feet  from 
the  missed  one. 

114 


DON'T  use  two  kinds  of  explosives  in  the  same  bore  hole,  except 
where  one  is  used  as  a  primer  to  detonate  the  other,  as 
where  dynamite  is  used  to  detonate  Judson  powder.  The 
quicker  explosive  may  open  cracks  in  the  rock  and  allow 
the  slower  to  blow  out  through  these  cracks,  doing  little  or 
no  work. 

DON'T  use  blasting  powder,  permissible  explosives  or  high  explos- 
ives in  the  same  bore  hole  in  coal  mines. 

DON'T  use  frozen  or  chilled  explosives.  Dynamite,  other  than 
Red  Cross,  often  freezes  at  a  temperature  between  45°  F. 
and  50°  F. 

DON'T  use  any  arrangement  for  thawing  dynamite  other  than  one 
of  those  recommended  by  the  DU  PONT  COMPANY. 

DON'T  thaw  dynamite  on  heated  stoves,  rocks,  bricks  or  metal,  or 
in  an  oven,  and  don't  thaw  dynamite  in  front  of,  near  or 
over  a  steam  boiler  or  fire  of  any  kind. 

DON'T  take  dynamite  into  or  near  a  blacksmith  shop  or  near  a 
forge  on  open  work. 

DON'T  put  dynamite  on  shelves  or  anything  else  directly  over 
steam  or  hot  water  pipes  or  other  heated  metal  surface. 

DON'T  cut  or  break  a  dynamite  cartridge  while  it  is  frozen,  and 
don't  rub  a  cartridge  of  dynamite  in  the  hands  to  complete 
thawing. 

DON'T  heat  a  thawing  house  with  pipes  containing  steam  under 
pressure. 

DON'T  place  a  hot  water  thawer  over  a  fire,  and  never  put  dynamite 
into  hot  water  or  allow  it  to  come  in  contact  with  steam. 

DON'T  allow  thawed  dynamite  to  remain  exposed  to  low  temper- 
ature, but  use  as  soon  as  possible. 

DON'T  allow  priming  (the  placing  of  a  blasting  cap  or  electric  fuze 
in  dynamite)  to  be  done  in  a  thawing  house. 

DON'T  prime  a  dynamite  cartridge  or  charge  or  connect  bore  holes 
for  electric  firing  during  the  immediate  approach  or  progress 
of  a  thunder  storm. 

115 


DON!T  carry  blasting  caps  or  electric  fuzes  in  your  pocket. 
DON'T  tap  or  otherwise  investigate  a  blasting  cap  or  electric  fuze. 

DON'T  attempt  to  take  blasting  caps  from  the  box  by  inserting  a 
wire,  nail  or  other  sharp  instrument. 

DON'T  try  to  withdraw  the  wires  from  an  electric  fuze. 

DON'T  fasten  a  blasting  cap  to  the  safety  fuse  with  the  teeth  or  by 
flattening  it  with  a  knife ;  use  a  cap  crimper. 

DON'T  keep  electric  fuzes,  blasting  machines  or  blasting  caps  in  a 
damp  place. 

DON'T  attempt  to  use  electric  fuzes  with  the  regular  insulation  in 
very  wet  work.  For  this  purpose  secure  "Victor  Water 
Proof "  or  "  Gutta  Percha  Covered  "  Electric  Fuzes. 

DON'T  worry  along  with  old,  broken  leading  wire  or  connecting 
wire.  A  new  supply  won't  cost  much  and  will  pay  for 
itself  many  times  over. 

DON'T  handle  safety  fuse  carelessly  in  cold  weather,  for  when  cold 
it  is  stiff  and  breaks  easily. 

DON'T  store  or  transport  blasting  caps  or  electric  fuzes  with  high 
explosives. 

DON'T  store  safety  fuse  in  a  hot  place,  as  this  may  dry  it  out  so 
that  uncoiling  will  break  it. 

DON'T  lace  safety  fuse  through  dynamite  cartridges.  This  practice 
is  frequently  responsible  for  the  burning  of  the  charge. 

DON'T  operate  blasting  machines  half  heartedly.  They  are  built 
to  be  operated  with  full  force.  They  must  be  kept  clean 
and  dry. 

DON'T  cut  the  safety  fuse  short  to  save  time.  It  is  a  dangerous 
economy. 

DON'T  expect  a  cheap  article  to  give  as  good  results  as  a  high 
grade  one. 

DON'T  expect  explosives  to  do  good  work  if  you  try  to  explode 
them  with  a  detonator  weaker  than  a  No.  6  (red  label). 

116 


Main  Office,  E.  L  du  Pont  de  Nemours  Ponder  Co. 
Wilmington,  Delaware,  U.  S.  A. 


117 


Select  the  Right  Dynamite 

For   Your 


It  is  of  vital  importance  to  every  consumer  of  dynamite 
that  he  use  the  particular  kind  and  grade  that  will  produce  the 
greatest  output  at  the  lowest  cost  and  with  the  highest  per- 
centage of  safety. 


Brands  of  Dynamite 

You  know  you  are  using  the  best  explosive  of  its  class  — 
the  logical  result  of  pure  materials,  up-to-date  methods  and 
skilled  labor,  combined  with  over  a  century's  experience  in  the 
explosive  business.  The  dynamite  that  is  sure  to  give  maximum 
results  at  a  minimum  expense. 

The  advice  of  our  corps  of  technical  experts  is  at  your 
service  without  charge  to  assist  you  in  determining  the  best 
dynamite  for  your  work. 

The  HIGH  EXPLOSIVES  CATALOGUE,  issued  by 

this  Company  as  a  companion  to  the  BLASTING  SUPPLIES 
CA  TALOGUE,  gives  the  fullest  information  about  the  various 
classes  of  High  Explosives  and  their  use  under  all  sorts  of 
conditions.  It  is  a  very  complete  and  up-to-date  handbook  on 
the  subject  of  High  Explosives,  and  should  be  in  the  hands  of 
everyone  interested  in  their  purchase  or  use.  Will  be  sent 
free  on  request. 

118 


BLASTING  POWDER 

THE  RESULT  OF  OVER  A  CENTURY'S  EXPERIENCE 

Scientific  incorporation  of  high  grade  materials  by  the  most 
modern  methods  and  expert  workmanship,  all  backed  by  our 
long  experience,  insure  for  users  of  (tjUjONj)  Blasting  Powder 

MAXIMUM    STRENGTH 
MINIMUM    SMOKE 


Made  in  two  grades,  with  a  total  of  fifteen  different  granu- 
lations, thus  offering  a  choice  amply  wide  for  every  requirement. 

If  you're  a  user  of  Blasting  Powder,  you  should  have  our 
Blasting  Powder  Catalogue,  a  practical  handbook  on  the  subject. 
Sent  free  on  request. 


119 


Farm  with  Dynamite 

THE  CHEAPEST   FARM    HELP  IN  THE  WORLD 


Dependable  Brands  of 
Dynamite 

WILL 

Dig  Ditches  Drain  Swamps  Fell  Trees 

Break  Hard  Pan  and  Subsoil 

Dig  Holes  for  ^  vii)/  Blast  Stumps 

Trees  and  Posts      .^^f  ..•^,/;JvA>i    .•  and  Boulders 

Split  Logs 

for  Rails  and          b^i 
Cord  Wood  ~,3 

lii 

Clear  Streams  of 

Ro.a. 

Excavate  for  Foundations,  Cellars  and  Flood  Gates 

Our  "Farming  with  'Dynamite"  f^ool^let  will  be  sent  free  on  request 

120 


W^l^'-tte*' 


For  Gaseous  or  Dusty  Coal  Mines 


THE   U.   S.    BUREAU    OF    MINES 
HAS    PASSED    A    NUMBER    OF 


Permissible  Explosives 


The  same  Permissible  won't  do  for  every  coal  mine. 
The  many  varying  conditions  call  for  a  wide  range   of 
explosives  if  high  production  is  to  be  secured  at  a  low  cost. 
There  is  a 

Monobel  or  Carbonite 

grade  exactly  suited  to  meet  every  condition  found  in  gaseous  or 
dusty  coal  mines. 

Our  High   Explosives  Catalogue  is  full  of  valuable  data 
for  Coal  Mine  Owners.     Sent  free  on  request. 

121 


Learn  Trap 
Shooting 

AN  ALL  YEAR 
ROUND  SPORT 


Closely  parallels  actual  hunting  conditions. 

The  open  air — the  sudden,  swift  flight  of  the  bird — the 
opportunity  for  quick,  accurate  shooting — all  combine  to  make 
trap  shooting 

Fascinating  and  Healthful 


Quickly  develops  the  new  shooter  into  a  skilled  shot 
because  of  the  opportunity  for  regular  and  continuous  practice 
under  favorable  conditions  and  pleasant  surroundings. 

Trap  shooting  keeps  the  old  hunter  from  getting  rusty 
between  game  seasons.  The  clay  pigeons  fly  every  day  in 
the  year. 

Join  your  local  gun  club.  If  there's  none  nearby, 
start  a  gun  club.  We  will  help. 

Our  Gun  Club  Booklet  explains  how  to  go  about  organ- 
izing a  club,  the  rules  of  the  game,  etc.  Write  for  it  It's  free. 

122 


SPORTING  POWDERS 

MAKE  AND  BREAK  RECORDS 
AT  THE  TRAPS 

and  are  Unequaled  in  the  Field 


Du  Pont  Smokeless  Sporting  Powders  are  chemically  pure 
and  will  not  pit  the  gun  barrels. 


RALLISTITF 

•^      A      PERFECT       ki 


DENSE   SMOKELESS  POWMJ1 


BULK  SMOKELESS  POWDER 


Rifles. 


Black    Sporting    Powders    unequaled    for  Shot  Gun    and 


Perfection  in  Sporting  Powders  is  only  obtained  by  the 
employment  of  the  most  skillful  workmen,  the  operation  of  the 
most  improved  machinery  and  the  exercise  of  the  most  scrupulous 
care  in  the  selection  and  preparation  of  raw  material. 

DuPont  Sporting  Powders  are  fully  guaranteed  by  the 
Pioneer  Powder  Makers  of  America. 

SPORTING  <POWDER  LITERATURE  SENT  ON  REQUEST 
123 


You  Can  Be  a  Crack  Shot 

WITH  RIFLE  OR  REVOLVER 
Only  Three  Things  Are  Necessary 

l  Good  Rifle  or 


The  best  is  the  cheapest.  Use  an  arm  whose  maker  has  a 
reputation  to  sustain. 

Jl  Reliable   Powder 

(tjUPONj)  Brands  of  Smokeless  Powders  are  the  ultimate  result 
of  combining  pure  materials,  modern  methods  and  skilled  labor, 
with  an  experience  in  powder  making  extending  over  a  century. 
They  are  as  nearly  1  00%  perfect  as  human  skill  can  make  them. 

A  Wcice  to    'Practice 

Nearly  all  the  states  will  gladly  allow  Civilian  Rifle  Clubs 
to  shoot  on  State  Ranges.  Write  us  for  information  how  to  form 
a  Civilian  Rifle  Club. 

If  for  any  reason  a  state  range  is  not  available,  why  not 
have  a  range  of  your  own?  We  will  gladly  furnish,  without 
charge,  blue  prints  for  indoor  or  outdoor  ranges. 


We  triage  a  Smokeless  Powder  especially 
fitted  to  meet  every  rifle  or  revolver  need 


Out  Rifle  Smokeless  Catalogue  is  yours  for  the  asking 

124 


Fabrikoid 

COSTS  LESS,   LOOKS  BETTER   THAN   AND 
WEARS  AS   WELL  AS  LEATHER 


Water  Proof        ^         Grease  Proof 
Sun  Proof  Durable 

Tough  and  Strong 


ALL  COLORS,  GRAINS  AND  WEIGHTS 

Rapidly  Displacing  Leather 

FOR 

BUGGY  TOPS        CUSHIONS          BACKS 

AUTO  TOP  COVERS  AND  SPARE  TIRE  CASES 

BUGGY  BOOTS         LAMP  COVERS         STORM  APRONS 

FURNITURE  UPHOLSTERING 
GO-CARTS  MURAL  DECORATIONS  TRUNKS 

BAGS    SUIT  CASES    GUN  CASES    CARD  CASES 

POCKET  BOOKS  BELTS  SPECTACLE  CASES 

MUSIC  ROLLS  BOOK  BINDING 


WRITE  FOR  INFORMATION  AND  SAMPLES 


FABRIKOID  WORKS,  NEWBURGH,  N.  Y. 

(E.  I.  duPont  de  Nemours  Powder  Co.,  Owner) 

125 


Pyroxylin  and  Its  Solvents 


The  use  of  strictly  high  grade  ingredients  exclusively, 
coupled  with  an  experience  of  over  thirty  years  in  the 
manufacture  of  Pyroxylin,  enables  us  to  offer 

AMYL  ACETATE 

REFINED  FUSEL  OIL 

ETHER,  U.S.  P.  of  1890 
BRONZING  LIQUIDS 

GAS  MANTLE  DIPS 

Pyroxylin  solutions,  of  all  strengths,  for  use  in  Patent 
Leather  Work  and  as  the  base  of  lacquers  and  enamels. 

Split  leather  solutions,  for  use  in  finishing  leather  splits. 

OF  HIGH  STABILITY  AND  UNIFORM  VISCOSITY 


We  have  three  plants,  available  for  manufacture  of 
Pyroxylin,  thus  insuring  continuity  of  supply.  Our  large  corps 
of  chemists  is  constantly  experimenting  along  improvement  and 
original  lines.  Probably  we  can  help  in  some  of  your  problems. 

Correspondence  solicited 

International  Smokeless  Powder  &  Chemical  Company 

WILMINGTON,  DELAWARE 

126 


A-7 

JST,    1911 
26M 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 

AN  INITIAL  FINE  OF  25  CENTS 


WILL  BE  ASSESSED   FOJ?    FA.  ILM^E;  TQ 

THIS    BOOK   ON    THE   DATE   DUE.    THE   PENALTY 

WILL  INCREASE  TO   5O  CENTS  ON  THE  FOURTH 

DAY    AND    TO    $1.OO    <5 

OVERDUE. 


OCT    3    1933 


FAR  20 

FAR  H  19749 


LD  21-100m-7,'33 


GAYLORD  BROS. 

I^^^I^^H 

SYRACUSE,-  M.Y. 


